FT MEADE 
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ROBERTS' 

Practice of Medicine. 

THE FIFTH ENLARGED EDITION. JUST READY. 

Recommended as a Text-book at University of Pennsylvania, Long Island 
College Hospital , Yale and Harvard Colleges, Bishop's College, Montreal, 
University of Michigan, and over twenty other Medical Schools. 

A HANDBOOK OF THE THEORY AND PRACTICE OF MEDICINE. 
By Frederick T. Roberts, m.d., m.r.c.p.. Professor of Materia Med- 
ica and Therapeutics and of Clinical Medicine in University College 
Hospital; Assistant Physician in Brompton Consumptive Hospital. The 
Fifth Edition, partially rewritten, and carefully revised throughout. 

Price, in'Cloth, $5.00; Leather, $6.00. 


“I have 
systematic, 
son, Jr., A 
“ It is w 
tioners, as 
compendiui 
Allen, Rus, 
“After d 
convinced < 
Yale Colleg 
“I have 
take pleasi 
in the hand 



lent simple, but 
’—E. D. Hud- 
V York. 

|nts and practi- 
It is a capital 
|lessor J. Adams 

ime thoroughly 
it to my class in 

book, and shall 
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the Practice op 

Aledicine, Ann Arbor University ,"iviicnigan. 

»“ I have never met with a work on Practice that seemed to me so well 
adapted for students. While concise, nothing is omitted that is important to 
be known.”- - Professor J. A . Thacker, Cincinnati. 

“ I sha! include it among the text-books of the College of Physicians and 
Surgeons, and strongly recommend it to my classes.”— Professor John S. 
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“ Our opinion of it is one of almost unqualified praise. The style is clear, 
and the amount of useful and, indeed, indispensable information which it con¬ 
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“ That Dr. Roberts’ book is admirably fitted to supply the want of a good 
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of a question.”— Students' Journal and Hospital Gazette. ' 

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FEB 11 1886 















YEO’S 

Manual of Physiology. 

300 ILLUSTRATIONS. 

FULL GLOSSARY AND INDEX. 

By Gerald F. Yeo, m.d., f.r.c.s., Professor of Physiology in 
King’s College, London. Demi-octavo, 750 pages. Over 
300 carefully printed engravings on wood. v 

Bound in Cloth, $4.00; Leather, $S.OO. 


RECOMMENDATIONS. 

“ By his excellent manual Prof. Yeo has supplied a want which must have been felt by 
every teacher of physiology. In the noble text-book of Prof. Foster, English readers have 
a work which is unsurpassed, but its great size and comprehensiveness, and its some¬ 
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of the first and second years’ students. Dr. Yeo has written a book which is intended for 
junior students, but which, although written in simple, and as far as possible untechnical 
language, is accurate and complete. * * * Moreover, being intended chiefly for medical 
students, and written by one who is not only an able physiologist, but an accomplished 
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is profusely illustrated with excellent wood engravings. * * * In conclusion, we heartily 
congratulate Prof. Yeo on his work, which we can recommend to all those who wish to 
find, within a moderate compass, a reliable and pleasantly written exposition of all the 
essential facts of physiology as the science now stands.”— The Dublin Journal of Medical 
Science, May, 1S84. 

“ For students’ use it is one of the very best text-books in Physiology.”— Prof. L. B. 
How, Dartmouth Medical College, Hanover , N. H. 

“The work will take a high-rank among the smaller text-books of Physiology.”— Prof 
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A MANUAL OF THE DISSECTION OF THE HUMAN 
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The object of this book is to explain to the student , in a plain, practical way , 
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THE ESSENTIALS OF PATHOLOGY. By D. Tod Gilliam, 
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HUMAN PHYSIOLOGY. 

THIRD EDITION. ILLUSTRATED. 


BRUBAKER. 



? QUIZ COMPENDS ? 

A NEW SERIES OF MANUALS FOR THE USE OF 
STUDENTS AND PHYSICIANS. 

Price of each, Cloth, $1.00. Interleaved, for taking Notes, $1.25. 

These Compends are based on the most popular text-books, and the 
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may thoroughly represent the present state of the subjects upon which they 
treat. 

The Authors have had large experience as Quiz Masters and attaches 
of colleges, and are well acquainted with the wants of students. 

They are arranged in the most approved form, thorough and concise, 
with illustrations whenever they can be used to advantage. 

Can be used by students of any college. 

8®” They contain information nowhere else collected in such a condensed, 
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Size is such that thry may be easily carried in the pocket, and the price 

is low. 

4 ®=* They will be found very serviceable to physicians as remem¬ 
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LIST OF VOLUMES. 

No. 1. ANATOMY. Third Edition. 63 Illustrations. By Samuel O. L. 

Potter, m.d., late A. A. Surgeon U. S. Army. 

No. 2. PRACTICE OF'M’EDICINE. Part I. Second Edition. Revised 
and Enlarged. By Dan’l E. Hughes, m.d., Demonstrator of Clinical Medi¬ 
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No 3. PRACTICE OF MEDICINE Part II. Second Edition. Revised 
and Enlarged. Same author as No. 2. 

No. 4. PHYSIOLOGY. Third Edition, with Illustrations. Enlarged and 
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No. 5. OBSTETRICS. Second Edition. Enlarged. By Henry G. Landis, 
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No. 6. MATERIA MEDICA. A New Revised Edition. By Samuel O. 

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No. 9. SURGERY. Second Edition. Revised and Enlarged. ByORViLLH 
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delphia. With 62 Illustrations. 

No. 10. ORGANIC CHEMISTRY. Including Medical Chemistry, Urine 
Analysis and the Analysis of Water and Food. By Henry Leffmann, 
m.d., Demonstrator of Chemistry in Jefferson College, Philadelphia. 

No. 11. PHARMACY. By F. E. Stewart, m.d.,ph.g., Quiz Master in 
Pharmacy and Chemistry, Philadelphia College of Pharmacy, Lecturer at 
the Medico Chirurgical College, etc. 

Others in preparation. 

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? QXJIZ-COMPENDS. ? No. 4. 



COMPEND 


HUMAN PHYSIOLOGY. 


ESPECIALLY ADAPTED FOR THE USE OF 
MEDICAL STUDENTS. 


/ 


BY 


ALBERT P. BRUBAKER, A.M., M.D., 

DEMONSTRATOR OF PHYSIOLOGY IN THE JEFFERSON MEDICAL COLLEGE; PROFESSOR 
OF PHYSIOLOGY, PENNSYLVANIA COLLEGE OF DENTAL SURGERY; 

MEMBER OF THE PATHOLOGICAL SOCIETY 


4 


OF PHILADELPHIA. 


THIRD EDITION, REVISED AND ENLARGED. 


WITH ILL USTRA TIONS, 


A TABLE OF PHYSIOLOGICAL CONSJ^CS.. \ 

11 1886 

PHILADELPHIA: 

P. BLAKISTON, SON & CO., 

1012 Walnut Street. 

1886. 






Entered according to Act of Congress, in the year 1886, by 
P. BLAKISTON, SON & CO., 

In the office of the Librarian of Congress, at Washington, D. C. 



PRESS OF WM. F. FELL & CO., 
1220-24 Sansom street. 







PREFACE TO SECOND EDITION. 


This Compend of Physiology is the outgrowth of the author’s system of 
examinations in the Quiz room during a number of years, and was written 
at the request of medical students who desired a compact and convenient 
arrangement of the fundamental facts of human physiology. As most 
medical students enter upon the study of physiology before they have ac¬ 
quired a thorough knowledge of anatomy, it was thought desirable that such 
anatomical details should also be inserted as would be essential to a clear 
conception of the functions about to be studied. It was believed that it 
would be practically useful to students during their attendance upon lectures 
and in reviewing the subject prior to examinations. The fact that during 
the first year after its publication the first edition has been exhausted, 
proves that it has met the needs of students. 

In preparing a second edition the author has carefully revised the en¬ 
tire work, and inserted some fifteen pages of additional matter, which it is 
hoped will still further increase the usefulness of the book. 

To those teachers of physiology who have kindly noticed and recom¬ 
mended the Compend to their students I tender m^ thanks, and trust that 
in its improved condition it will continue to merit their approval. 

ALBERT P. BRUBAKER. 


PREFACE TO THIRD EDITION. 


A third edition of the Compend having been called for, the author has 
taken the opportunity to make some alteration to the text, to add some new 
material, and to insert a number of illustrations, which it is hoped will 
elucidate the text. 

1210 Race Street. 

February, 1886. 


A. P. B. 





TO MY FATHER 


HENRY BRUBAKER, A.M., M.D., 

THIS LITTLE VOLUME 

IS AFFECTIONATELY INSCRIBED. 







TABLE OF CONTENTS 


PAGE 

Introduction. 9 

Chemical Composition of the Body. 10 

Structural Composition of the Body . ic 

Food. 18 

Digestion. 23 

Absorption. 33 

Blood. 39 

Circulation of Blood. 45 

Respiration. 52 

Animal Heat. 58 

Secretion. 60 

Mammary Glands. 63 

Vascular or Ductless Glands. 65 

Excretion. 66 

Kidneys. 66 

Liver. 73 

Skin. 76 

Nervous System. 80 

Spinal Nerves.. 82 

Properties and Functions of Nerves. 84 

Cranial Nerves. 87 

Spinal Cord. 101 

Medulla Oblongata. 109 

Pons Varolii. 112 

Crura Cerebri. 113 

Corpora Quadrigemina. 114 

Corpora Striata and Optic Thalami. 114 






























TABLE OF CONTENTS. 


viii 

PAGE 

Cerebellum. 116 

Cerebrum. 118 

Sympathetic Nervous System. 123 

Sense of Touch. 126 

Sense of Taste. 127 

Sense of Smell. 129 

Sense of Sight. 130 

Sense of Hearing. 136 

Voice and Speech. 141 

Reproduction. 144 

Generative Organs of the Female. 144 

Generative Organs of the Male. 147 

Development of Accessory Structures. 148 

Development of the Embryo. 153 

Table of Physiological Constants. 159 

Table showing Relation of Weights and Measures of the 
Metric System to Approximate Weights and Measures 

of the U. S. 162 

Index. 163 



















COMPEND 


OF 

HUMAN PHYSIOLOGY. 


Physiology, from (pu<Jt $, nature, and a discourse, in its original 

application embraced the study of all natural objects, inorganic as well as 
organic. In its modern application physiology signifies the study of life; 
the investigation of the vital phenomena exhibited by all organic bodies, 
vegetable and animal. 

It may be divided into— 

1. Vegetable physiology, which treats of the phenomena manifested by 
the several structures of which the plant is composed. 

2. Animal physiology , which treats of the phenomena manifested by the 
organs and tissues of which the animal body is composed. 

Human Physiology is the study of the functions exhibited by the 
human body in a state of health. 

A Function is the action of an organ or tissue. 

The Functions of the Human Body may be classified into three 
groups, viz.:— 

1. Nutritive functions, which, have for their object the preservation of 
the individual; e.g ., digestion, absorption, circulation of the blood, 
respiration, assimilation, animal heat, secretion and excretion. 

2. Animal functions, which bring the individual into conscious relation¬ 
ship with external nature; e.g., sensation, motion, language, mental 
and moral manifestations. 

3. Reproductive function, which has for its object the preservation of 
the species. 

The facts of human physiology have been determined by means of 
anatomy, chemistry, pathology, comparative anatomy, vivisection, the 
application of physics, etc. 

The Body may be studied from a chemical and structural point of view. 
b 9 



10 


HUMAN PHYSIOLOGY. 


CHEMICAL COMPOSITION OF THE HUMAN 

BODY. 


Of the Sixty-four Chemical Elements, about sixteen enter into the 
composition of the body, in the following proportions:— 


Oxygen.. 

..72.00 , 

0 . H. and C. are found in all the tissues and 

Hydrogen. 

,. 9.10 

1 fluids of the body, without exception. 

Nitrogen. 

.. 2.50 

j 0 . H. C. and N. fouhd in most of the fluids 

Carbon. 

.. 13-50 

' and all tissues except fat. 

Sulphur.. 

.. .147 .... 

..In fibrin, casein, albumen, gelatin; as potas- 
sium sulpho-cyanide in saliva; as alkaline 
sulphate in urine and sweat. 

Phosphorus.. 

.. 1.15 .... 

In fibrin and albumen; in brain; as tri-sodium 
phosphate in blood and saliva, etc. 

Calcium. 

.. 1.30 .... 

..As calcium phosphate in lymph, chyle, blood, 
saliva, bones and teeth. 

Sodium. 

.. .10 

,..As sodium chloride in all fluids and solids of 
the body, except enamel; as sodium sul¬ 
phate and phosphate in blood and muscles. 

Potassium.... 

.. .026 ... 

...As potassium chloride in muscles; generally 
found with sodium as sulphates and phos¬ 
phates. 

Magnesium.. 

.. .001 ... 

...Generally in association with calcium, as phos- 
phate, in bones. 

Chlorine. 

.. .085 ... 

...In combination with sodium, potassium and 
other bases, in all the fluids and solids. 

Fluorine. 

.. .08 

...As calcium fluoride in bones, teeth and urine. 

Iron. 


...In blood globules; as peroxide in muscles. 

Silicon. 


...In blood, bones and hair. 

Manganesium, a trace ... 

...Probably in hair, bones and nails. 


Of the four chief elements which together make up 97 per cent, of the 
body, O. H. N. are eminently mobile, elastic , and possess great atomic heat. 
C. H. N. are distinguished for the narrow range and feebleness of their 
affinities and chemical inertia. C. has the greatest atomic cohesion. O. 
is noted for the number and intensity of its combinations, and its remark¬ 
able display of chemical activity. 

Chemical Elements do not exist alone in the body, but are combined 
in characteristic proportions to form compounds, the proximate principles, 
which are the ultimate compounds to which the fluids and solids can be 
reduced. 

























CHEMICAL COMPOSITION OF THE HUMAN BODY. H 

Proximate Principles exist in the body under their own form, and can 
be extracted without losing their distinctive properties. 

There are about one hundred proximate principles, which are divided 
into four classes, viz.: inorganic , organic non-nitrogenized, organic nitro- 
genized , and principles of waste. 

I. INORGANIC PROXIMATE PRINCIPLES. 

WHERE FOUND. 

Lungs and blood. 

Stomach and intestines. 

Blood and intestines. 

Expired air of lungs. 

Lungs and intestines. 

Found in all solids and fluids. 

In all fluids and solids except enamel. 

In muscles, liver, saliva, gastric juice, etc. 
Gastric juice, saliva, tears, urine. 

Bones, teeth, urine. 

Bones, teeth, cartilage, internal ear, blood. 

In all fluids and solids of the body. 

Universal, except milk, bile and gastric juice. 

Blood, bones, lymph, urine, etc. 

Blood and sebaceous matter. 

The inorganic principles enter and leave the body under their own 
form. Water is an essential constituent of all the tissues of the body, 
constituting about 70 per cent, of the entire body weight. It is introduced 
into the body in the form of drink and as a constituent of all kinds of 
food. The average quantity consumed daily is about four pints. While 
in the body, water acts as a general solvent, gives pliability to various 
tissues, and promotes the passage of inorganic and organic matters through 
animal membranes. It also promotes chemical changes which are essen¬ 
tial to absorption and assimilation of food and the elimination of products 
of waste. It is probable that water is also formed within the body by the 


Oxygen. 

Hydrogen. 

Nitrogen. 

Carbonic anhydride. 

Carburetted hydrogen 'j 
Sulphuretted hydrogen/ 

Water... 

Sodium chloride. 

Potassium chloride. 

Ammonium chloride. 

Calcium chloride. 

Calcium carbonate. 

Calcium phosphate 
Magnesium phosphate 
Sodium phosphate 
Potassium phosphate 
Sodium sulphate 
Potassium sulphate 
Sodium carbonate 
Potassium carbonate 
Magnesium carbonate.. 














12 


HUMAN PHYSIOLOGY. 


union of oxygen with the surplus hydrogen of the food. It is eliminated 
by the skin, lungs and kidneys. 

Sodium chloride is present in all the solids and fluids of the body, with 
the exception of enamel. It regulates osmotic action, holds the albuminous 
principles of the blood in solution, and preserves the form and consistence 
of blood corpuscles and the cellular elements of the tissues, by regulating 
the amount of water entering into their composition. 

Calcium phosphate is the most abundant of all the inorganic principles 
with the exception of water, and is present to a great extent in bone, teeth, 
muscles and milk. It gives the requisite consistency and solidity to the 
different tissues and organs. In the blood, it is held in solution by the 
albuminous constituents. 

The Sodium and Potassium phosphates are present in most of the solids 
and fluids, and give to them their alkaline reaction. They are chiefly 
derived from the food. 

II. ORGANIC NON-NITROGENIZED PRINCIPLES. 

The organic non-nitrogenized principles are derived mainly from the 
vegetable world, but are also produced within the animal body. They 
are divided into: 1st the carbo-hydrates , comprising starch and sugar, 
bodies in which the oxygen and hydrogen exist in the proportion to 
form water, the amount of carbon being variable; 2d, the hydro-carbons , 
comprising fats, bodies having the same elements entering into their 
composition, but with the carbon and hydrogen increased and the oxygen 
diminished in amount. 

SUGARS. C. O. H. 

Glycogen, or Liver sugar. 

Lactose, or Milk sugar. 

Glucose, or Grape sugar. 

Inosite, or Muscle sugar. 

Sugar is found in many of the tissues and fluids of the body; e.g ., liver, 
milk, placenta, blood, muscles, etc. The varieties of sugar are soluble in 
water, assume the crystalline form upon evaporation, and are converted 
into alcohol and carbonic acid by fermentation. Sugar is derived from 
the food, absorbed into the blood, where it largely disappears. After 
playing its part in the nutritive processes of the body, it is oxidized, and 
thus contributes to the formation of heat. It is finally eliminated under 
the form of carbonic acid and water. There is no experimental proof 
that sugar contributes directly to the formation of fat in the animal body. 


CHEMICAL COMPOSITION OF THE HUMAN BODY. 


13 


FATS. C. O. H. 



The Neutral fats, when combined in proper proportions, constitute a 
large part of the fatty tissue of the body; they are soluble in ether, chloro¬ 
form and hot alcohol; insoluble in cold alcohol and water, and liquefy at 
a high temperature; when a neutral fat is subjected to a high temperature 
in the presence of water and an alkali, it is decomposed, with the assimi¬ 
lation of water, into a fatty acid and glycerine. The fatty acid combines 
with the alkali and forms an oleate, palmitate or stearate, according to 
the fat used. A similar decomposition of the neutral fats is said to take 
place in the small intestine during digestion. When thoroughly mixed 
with pancreatic juice, the fats are reduced to a condition of emulsion, a 
state in which the fat is minutely subdivided and the small globules held 
in suspension. 

The Fatty acids combined with sodium, potassium and calcium, are 
found as salts in various fluids of the body, such as blood, chyle, faeces, 
etc. Phosphorized fats in nervous tissue, butyric acid in milk, propionic 
acid in sweat, are also constituents of the body. 

The Fats are derived from the food, both animal and vegetable. They 
are deposited in the form of small globules in the cells of the different 
tissues, are suspended in various fluids, are deposited in masses in and 
around various anatomical structures and beneath the skin. Independent 
of the fat consumed as food, there is good experimental evidence that fat 
is also produced within the animal body from a partial decomposition of 
the albuminous compounds. Fat serves as a non-conductor of heat, gives 
roundness and form to the body, and protects various structures from 
injury. The fats are ultimately oxidized, thus giving rise to heat and 
force, and are finally eliminated as carbonic acid and water. 


III. ORGANIC NITROGENIZED PRINCIPLES, 


ALBUMENS. C. O. H. N. S. P. 


Myosin. 

Protagon, 

Pepsin. 


Mucin. 

Chondrin 

Elastin. 

Keratin. 

Globulin. 


Albumen. 

Albuminose. 


Fibrin. 

Casein. 

Ostein. 


Pancreatin. 

Salivin. 


The Albuminous compounds are organic in their origin, being derived 
from the animal and vegetable world; they are taken into the body as 


y 


14 


HUMAN PHYSIOLOGY. 


food, appropriated by the tissues, and constitute their organic basis; they 
differ from the non-nitrogenized substances in not being crystalline, but 
amorphous, in having a more complex but just as definite composition, and 
containing in addition to C. O. H., nitrogen, with, at times, sulphur and 
phosphorus. The albumens possess characteristics which distinguish 
them from all other substances: viz., a molecular mobility , which permits 
isomeric modifications to take place with great facility. Under favorable 
conditions they promote chemical changes, by their presence (, catalysis ), in 
other substances: e. g ., during digestion, salivin and pepsin cause starch 
and albumen to be transformed into sugar and albuminose respectively. 
Different albumens possess varying proportions of water, which they lose 
when subjected to desiccation, becoming solid; but upon exposure to 
moisture they again absorb water, regaining their original condition—they 
are hygroscopic. Another property is that of coagulation , which takes 
place under certain conditions : e. g., the presence of mineral acids, heat, 
alcohol, etc. 

After death the albuminous compounds undergo putrefactive changes, 
giving rise to carburetted and sulphuretted hydrogen and other gases. 

Albumen exists in the blood, lymph, chyle, constituting the pabulum of 
the tissues; it is coagulated by heat, mineral acids and alcohol. 

Peptones are formed in the stomach from the digestion of albuminous 
principles of the food; they are coagulated by tannic acid, chlorine, acetate 
of lead, and characterized by great diffusibility, which permits them to 
pass through animal membranes with facility. 

Fibrin can be obtained from freshly drawn blood by whipping; it also 
coagulates spontaneously, and when examined microscopically exhibits a 
filamentous structure. 

Casein is the albuminous principle of milk. 

Ostein constitutes the organic basis of bone, with which are mingled the 
salts of lime. 

Myosin is found in muscles, protagon in brain, pepsin , pancreatin and 
salivin, in the digestive fluids. 

Mucin , chondrin , elastin, keratin and globulin , are found in mucus, 
cartilage, elastic tissues, hair, nails, and red corpuscles, respectively. 

As the properties of the compounds formed by the union of elements are 
the resultants of the properties of the elements themselves, it follows that 
the ternary substances, sugars, starches and fats, possess a great inertia and 
a notable instability; while in the more complex albuminous compounds, 
in which sulphur and phosphorus are united to the four chief elements, 
molecular mobility, resulting in isomerism, exists in a high degree. As 


STRUCTURAL COMPOSITION OF THE BODY. 


16 


these compounds are unstable, of a great molecular mobility, they are well 
fitted to take part in the composition of organic bodies, in which there is 
a continual movement of composition and decomposition. 


Urea, 

Creatin, 

Creatinin, 

Cholesterin, 


IV. PRINCIPLES OF WASTE. 


Xanthin, 

Tyrosin, 

Hippuric Acid, 
Calcium Oxalate, 


Sodium, 

Potassium, 

Ammonium, 

Calcium, 


- Urates. 


These principles, which represent waste, are of organic origin, arising 
within the body as products of disassimilation or retrograde metamorphosis 
of the tissues; they are absorbed by the blood, carried to the various 
excretory organs, and by them eliminated from the body. 

The excrementitious substances will be fully considered under excretion. 


Proximate Quantity of the Chemical Elements and Proximate 
Principles of Body Weighing 154 lbs. 



lbs. 

oz. 


lbs. 

oz. 

Oxygen. 

. ill 

.. 

Water. 


.. 

Hydrogen. 


.. 

Albuminoids. 

.. 23 

7 

Nitrogen. 

. 3 

8 

Fats. 


.. 

Carbon. 


.. 

Calcium phosphate. 

.. 5 

13 

Calcium. 


.. 

Calcium carbonate. 


.. 

Phosphorus. 


12 

Calcium fluoride. 


3 

Sodium, etc. 

154 

12 

Sodium sulphate, etc... 

i54 

9 


STRUCTURAL COMPOSITION of THE BODY. 

The Study of the Structure of the body reveals that it is composed 
of dissimilar parts, e.g., bones, muscles, nerves, lungs, etc.; while these, 
again, by closer examination, can be resolved into elementary structures, 
the tissues, e.g., connective tissue, muscular, nervous, epithelial tissue, etc. 

Microscopical examination of the tissues shows that they are com¬ 
posed of fundamental structural elements, termed cells. 

Cells are living physiological units; the simplest structural forms capable 
of manifesting the phenomena of life. 

Cells vary in their anatomical constitution in the different structures of 
the body, and may be classed in three groups, viz.: 1. Cells possessing a 
distinct cell wall, cell substance and a nucleus. 2. Cells possessing a cell 



















16 


HUMAN PHYSIOLOGY. 


substance and a nucleus. 3. Cells possessing the cell substance only. 
They vary in size, from the to the 3^ of an inch in diameter; when 
young and free to move in a fluid medium they assume the spherical form; 
but when subjected to pressure, may become flattened, cylindrical, fusiform 
or stellate. 

Structure of Cells. The cell wall is not an essential structure, as 
many cells are entirely devoid of it. It is a thin, structureless, transparent 
membrane, permeable to fluids. 

The Cell Substance in young cells is a soft, viscid, albuminous matter, 
unstable, insoluble in water, and known as protoplasm , bioplasm , sarcode, 
etc.; in older cells the original cell substance undergoes various trans¬ 
formations, and is partly replaced by fat globules, pigment and crystals. 

The Nucleus is a small vesicular body in the interior of the cell sub¬ 
stance, and frequently contains smaller bodies, the nucleoli. 

MANIFESTATIONS OF CELL LIFE. 

Growth. Cells when newly formed are exceedingly small, but as they 
approach maturity they increase in size, by the capability which the cells 
possess of selecting and appropriating new material as food, vitalizing and 
organizing it. The extent of cell growth varies in different tissues; in 
some the cells remain exceedingly small, in others they attain considerable 
size. In many instances the cell substance undergoes transformation into 
new compounds destined for some ulterior purpose. 

Reproduction. Like all organic structures cells have a limited period 
of life ; their continual decay and death necessitates a capability of repro¬ 
duction. Cells reproduce themselves in the higher animals mainly by 
Ussion. This is seen in the white blood corpuscles of the young embryos 
of animals; the corpuscle here consists of a cell substance and nucleus. 
When division of the cell is about to take place, the nucleus elongates, 
the cell substance assumes the oval form, a constriction occurs, which 
gradually deepens, until the original cell is completely divided and two 
new cells are formed, each of which soon grows to the size of the parent 
cell. 

In cells provided with a cell membrane the process is somewhat different. 
In the ova of the inferior animals, after fertilization has taken place, a 
furrow appears on the opposite sides of the cell substance, which deepens 
until the cell is divided into two equal halves, each containing a nucleus; 
this process is again repeated until there are four cells, then eight, and so 
on until the entire cell substance is divided into a mulberry mass of cells, 


STRUCTURAL COMPOSITION OF THE BODY. 


17 


completely occupying the interior of the cell membrane. The whole 
process of segmentation takes place with great rapidity, occupying not 
more than a few minutes, in all probability. 

Motion. Spontaneous movement has been observed in many of the 
cells of the body. It may be studied, for example, in the movements of 
the spermatozoids, the waving of the cilia covering the cells of the bronchial 
mucous membrane, the white corpuscles of the blood, etc. 

By a combination and transformation of these original structural elements, 
and material derived from them, all the tissues are formed which enter 
into the structure of the human body. 

CLASSIFICATION OF TISSUES. 

I. Homogeneous Substance, a more or less solid, albuminous struc¬ 
ture, filling the spaces between the cells and fibres of various tissues, e.g., 
cartilage, bone, dentine, etc. 

II. Limiting Membrane, a thin, homogeneous membrane, structure¬ 
less, composed of coagulated albumen, and often not more than the 

of an inch in thickness, found lining the blood vessels and lymphatics, 
forming the basement membrane of the skin and mucous membranes, the 
posterior layer of the cornea, the capsule of the crystalline lens, etc. 

III. Simple fibrous or filamentous tissue —the elements of which 
are real or apparent filaments. 

(a) Connective or areolar; white fibrous tissue; constituting tendons, 
ligaments, aponeuroses, periosteum, dura mater, synovial membranes, 
vascular tunics, etc. 

(b) Yellow elastic tissue , found in the middle coats of arteries, veins, 
lymphatics, ligamentum nuchse, vocal cords, ligamenta subflava, etc. 

IV. Compound membranes (membrano-cellular or fibro-cellular 
tissues), cells aggregated into laminae. 

(a) Epidermic tissue; (b) epithelial tissue; (c) glandular tissue; (d) 
cornea. 

V. Cells containing coloring matter, or pigment cells, e. g., skin, 
choroid membrane, etc. 

VI. Cells coalesced or consolidated by internal deposits, e. g., 
hair, nails, bone, teeth, etc. 

VII. Cells imbedded in an intercellular substance, e.g., cartilage, 
crystalline lens, etc. 

VIII. Cells aggregated in clusters, forming tissues more or less 
solid, e. g., adipose tissue, lymphatic glands. 


18 


HUMAN PHYSIOLOGY. 


IX. Cells imbedded in a matrix of capillaries, e. g ., gray or vesicular 
nervous matter. 

X. Cells whose coalesced cavities form tubes containing liquids or 
secondary solid deposits, e.g., vascular tissue, dentine. 

XI. Cells free, isolated, or floating—fluid tissue— e.g., red and white 
blood corpuscles, lymph and chyle corpuscles. 

FOOD. 

A Food may be defined to be any substance capable of playing a part 
in the nutrition of the body. 

Food is required for the repair of the waste of the tissues consequent on 
their functional activity, for the generation of heat and the evolution of force. 

Hunger and Thirst are sensations which indicate the necessity for 
taking food; they arise in the tissues at large, and are referred to the 
stomach and fauces, respectively, through the sympathetic nervous system. 

Inanition or Starvation results from an insufficiency or absence of 
food, the physiological effects of which are hunger, intense thirst, intestinal 
uneasiness, weakness and emaciation; the quantity of carbonic acid ex¬ 
haled diminishes and the urine is lessened in amount; the volume of the 
blood diminishes; a fetid odor is exhaled from the body; vertigo, stupor 
followed by delirium, and at times convulsions, result from a disturbance 
of the nerve centres; a marked fall of the bodily temperature occurs, from 
a diminished activity of the nutritive process. Death usually takes place, 
from exhaustion. 

During starvation the loss of different tissues, before death occurs, 
averages T 4 ^, or 40 per cent, of their weight. 

Those tissues which lose more than 40 per eent. are fat, 93.3; blood, 75; 
spleen, 71.4; pancreas, 64.1; liver, 52; heart, 44.8; intestines, 42.4; 
muscles, 42.3. Those which lose less than 40 per cent, are the muscular 
coat of the stomach, 39.7; pharynx and oesophagus, 34.2; skin, 33.3; 
kidneys, 31.9; respiratory apparatus, 22.2; bones, 16.7; eyes, 10; nervous 
system, 1.9. 

The Fat entirely disappears, with the exception of a small quantity 
which remains in the posterior portion of the orbits and around the 
kidneys. The Blood diminishes in volume and loses its nutritive proper¬ 
ties. The Muscles undergo a marked diminution in volume and become 
soft and flabby. The Nervous system is last to suffer, not more than two 
per cent, disappearing before death occurs. 


FOOD. 


19 


The appearances presented by the body after death from starvation are 
those of anaemia and great emaciation; almost total absence of fat; blood¬ 
lessness ; a diminution in the volume of the organs; an empty condition 
of the stomach and bowels, the coats of which are thin and transparent. 
There is a marked disposition of the body to undergo decomposition, 
giving rise to a very fetid odor. 

The duration of life after a complete deprivation of food varies from 
eight to thirteen days, though life can be maintained much longer if a 
quantity of water be obtained. The water is more essential under these 
circumstances than the solid matters, which can be supplied by the 
organism itself. 

The different alimentary principles which are appropriated by the 
system are combined in different proportions in the various articles of 
food, and are separated from the innutritious substances during the 
process of digestion. They belong to the organic and inorganic worlds, 
and may be classified, according to their chemical composition, as 
follows :— 


CLASSIFICATION OF ALIMENTARY PRINCIPLES, 

i. Albuminous group—nitrogenized, C. O. H. N. S. P. 


PRINCIPLE. WHERE FOUND. 

Myosin, syntonin . Flesh of animals. 

Vitellin, albumen . Yolk of egg, white of egg. 

Fibrin, globulin . Blood contained in meat. 

Casein . Milk, cheese. 

Gluten . Grain of wheat and other cereals. 

Vegetable albumen . Soft growing vegetables. 

Legumin . Peas, beans, lentils, etc. 

Gelatin . Bones. 


2. Saccharine group—non-nitrogenized, C. O. H. 

Cane sugar, beet root sugar . Sugar cane, beets, etc. 

Glucose, grape sugar . Fruits. 

Inosite, liver sugar, glycogen . Muscles, liver, etc. 

Lactose or milk sugar . Milk. 

Starch . Cereals, tuberous roots and legu¬ 

minous plants. 

3. Oleaginous group—non-nitrogenized, C. O. H. 

Animal fats and oils . ^ Found in the adipose tissue of ani- 

Stearin, olein . Y mals, seeds, grains, nuts, fruits, 

Palmatin, fatty acids . J and other vegetable tissues. 


















20 


HUMAN PHYSIOLOGY. 


4. Inorganic group. Water, sodium and potassium chlorides, sodium, 
calcium, magnesium and potassium phosphates, calcium carbonate and 
iron. 

5. Vegetable acid group. Malic, citric, tartaric and other acids, 
found principally in fruits. 

6. Accessory foods. Tea, coffee, alcohol, cocoa, etc. 

The Albuminous principles enter largely into the composition of the 
body, and constitute the organic bases of the different tissues; they are 
mainly required for the growth and repair of the tissues. There is good 
reason to believe that the albuminous principles are decomposed in the 
body into fat and urea, and the former when oxidized gives rise to the 
evolution of heat and force, while the latter is eliminated by the kidneys. 
Muscular work, however, does not result from a destruction of the albu¬ 
minous compounds. The oxidation of the carbonaceous compounds, 
sugars and oils, furnishing the force which is transformed by the muscular 
system into motor power. When employed exclusively as food for any 
length of time, the albuminous substances are incapable of supporting 
life. 

The Saccharine principles are important to the process of nutrition, 
but the changes which they undergo are not fully understood; they 
form but a small proportion of the animal tissues, and by oxidation 
generate heat and force. Starch undergoes conversion into dextrin and 
grape sugar. 

The Oleaginous principles form a large part of the tissues of the body. 
They are introduced into the system as food, and are formed also from a 
transformation of albuminous matter during the nutritive process; they 
enter into the composition of nervous and muscular tissue, and are stored 
up as adipose tissue in the visceral cavities and subcutaneous connective 
tissue, thus giving roundness to the form and preventing, to some extent, 
the radiation of heat. While they aid in the reconstruction of tissue, they 
mainly undergo oxidation, giving rise to the production of heat and the 
evolution of muscular and nervous force. 

The Inorganic principles constitute an essential part of all animal tissues, 
and are introduced with the food. 

Water is present in all fluids and solids of the body, holding their 
ingredients in solution, promoting the absorption of new material into the 
blood and tissues, and the removal of waste ingredients. 

Sodium chloride is an essential constituent of all tissues, regulating the 
passage of fluids through animal membranes (endosmosis and exosmosis). 


FOOD. 


21 


Calcium phosphate gives solidity to bones and teeth, constituting more 
than one-half their substance. 

Iron is a constituent of the coloring matter of the blood. 

The Vegetable acids are important to nutrition, and tend to prevent the 
scorbutic diathesis. 

The Accessory foods also influence the process of nutrition. Tea excites 
the respiratory function, increasing the elimination of carbonic acid. Coffee 
is a stimulant to the nervous system; increases the force of the heart’s 
action, increases the arterial tension and retards waste. 

Alcohol , when introduced into the system in small quantities , undergoes 
oxidation and contributes to the production of force, and is thus far a food. 
It excites the gastric glands to increased secretion, improves the digestion, 
accelerates the action of the heart and stimulates the activities of the 
nervous centres. In zymotic diseases, and all cases of depression of the 
vital powers, it is most useful as a restorative agent. When taken in 
excessive quantities , it is eliminated by the lungs and kidneys. The 
metamorphosis of the tissues is retarded, the elimination of urea and 
carbonic acid is lessened, the temperature lowered, the muscular powers 
impaired and the resistance to depressing external influences diminished. 
When taken through a long period of time, alcohol impair* digestion, 
produces gastric catarrh, disorders the secreting power of the hepatic cells. 
It also diminishes the muscular power and destroys the structure and 
composition of the cells of the brain and spinal cord. The connective 
tissue of the body increases in amount, and subsequently contracting, gives 
rise to sclerosis. 

A proper combination of different alimentary principles is essential 
for healthy nutrition; no one class being capable of maintaining life for 
any definite length of time. 

The Albuminous food in excess promotes the arthritic diathesis, mani¬ 
festing itself as gout, gravel, etc. 

The Oleaginous food in excess gives rise to the bilious diathesis, while 
a deficiency of it promotes the scrofulous. 

The Farinaceous food , when long continued in excess, favors the rheu¬ 
matic diathesis by the development of lactic acid. 

The Alimentary Principles are not introduced into the body as such, 
but are combined in -proper proportions to form compound substances, 
termed foods , e. g., bread, milk, eggs, meat, etc., the nutritive value of 
each depending upon the extent to which these principles exist. 


22 


HUMAN PHYSIOLOGY. 


PERCENTAGE COMPOSITION OF DIFFERENT FOODS. 



WATER. ALBUMEN. 

STARCH. 

SUGAR. 

FATS. 

SALTS. 

Bread . 

. 37 8.1 

47-4 

3-6 

1.6 

2-3 

Milk. 

.. 86 4.1 

... 

5-2 

3-9 

0.8 

Eggs. 

.. 74 I 4 -° 

... 

... 

i °-5 

i -5 

Meat. 


... 

... 

15-45 

2.95 

Potatoes . 

. 75 2.1 

18.8 

3-2 

0.2 

0.7 

Corn . 

. 14 11.1 

64.7 

0.4 

8.1 

i *7 

Oatmeal . 

. 15 J 2.6 

58.4 

5-4 

5-6 

3 

Turnips . 

. 91 1.2 

5 -i 

2.1 

... 

6 

Carrots . 

. 83 I.3 

8.4 

6.1 

0.2 

1.0 

Rice. . 

. 13 6.3 

79.1 

0.4 

0.7 

0-5 


The Amount of food required in 24 hours has been estimated at about 
pounds, comprising meat, 16 oz.; bread, 19 oz.; fat, 3^ oz.; water, 
52 fluid oz. 

In the excreta of the body the normal proportion of nitrogen to carbon 
is 1 to 15. To maintain this relation, a proper proportion of nitrogenized 
to carbonaceous food should be observed in diet. The proportion in the 
excreta would be— 

On a meat diet. nitrogen 1 to carbon 3 

On a bread diet. “ 1 “ 30 

On a mixed diet... “ 2 “ 33 

Or. “ 1 “ 16 

The amount of nitrogen and carbon necessary to compensate for the 
loss would be contained in 16 oz. of meat and 2 lbs. of bread; as, however, 
usually 3 oz. of oil are consumed in 24 hours, only 19 oz. of bread are 
required. 

COMPARISON OF INGESTA AND EGESTA IN 24 HOURS. 


FOOD, DRINK, AIR. 

oz. 

EXCRETIONS. 

OZ. 

Albumen. 

Starch. 


Breath (carbonic acid | . 

( watery vapor / 

. 4340 

Fats. 

Salts. 

. 3-17 

. I.I 3 

Perspiration ( carbonic acid ( 

r watery vapor J 

► 23.62 

Water (6 pints). 


Urine . . 


Oxygen. 


Solid excreta. 


Total. 

. 13940 

Total. 

..13940 





























DIGESTION. 


23 


DIGESTION. 

Digestion is a physical and chemical process, by which the food is 
changed, by the action of solvent fluids, into a form capable of being 
absorbed into the blood. 

The Digestive Apparatus consists of the alimentary canal and its 
appendages, viz.: teeth, salivary, gastric and intestinal glands, liver and 
pancreas. 

Digestion may be divided into seven stages: prehension, mastication, 
insalivation, deglutition, gastric and intestinal digestion and defecation. 

Prehension, the act of conveying food into the mouth, is accomplished 
by the hands, lips and teeth. 

Mastication is the trituration of the food, and is accomplished by 
the teeth and lower jaw, under the influence of muscular contraction. 
When thoroughly divided, the food presents a greater surface for the 
solvent action of the digestive fluids, thus aiding the general process of 
digestion. 

The Teeth are thirty-two in number, sixteen in each jaw, and divided 
into four incisors or cutting teeth, two canines, four bicuspids, and six 
molars or grinding teeth; each tooth consists of a crown covered by 
enamel, a neck, and a root surrounded by the crusta petrosa, and imbedded 
in the alveolar process; a section through a tooth shows that its substance 
is made up of dentine , in the centre of which is the pulp cavity, containing 
blood vessels and nerves. 

The lower jaw is capable of making a downward and an upward, a 
lateral and an antero-posterior movement, dependent upon the construction 
of the temporo-maxillary articulation. 

The jaw is depressed by the contraction of the digastric , genio-hyoid , 
mylo-hyoid and platysma myoides muscles; elevated by the temporal , 
masseter and internal pterygoid muscles; moved laterally by the alternate 
contraction of the external pterygoid muscles; moved anteriorly by the 
pterygoid and posteriorly by the united actions of the genio-hyoid, mylo¬ 
hyoid and posterior fibres of the temporal muscle. 

The food is kept between the teeth by the intrinsic and extrinsic mus¬ 
cles of the tongue from within, and the orbicularis oris and buccinator 
muscles from without. 

The Movements of Mastication are called forth by refiex action 
through the medulla oblongata, induced by the presence of food in the 
mouth. 


24 


HUMAN PHYSIOLOGY. 


NERVOUS CIRCLE OF MASTICATION 


AFFERENT OR EXCITOR NERVES. 

1. Lingual branch of 5th pair. 

2. Glosso-pharyngeal. 


1. 3d branch of 5th pair. 

2. Hypo-glossal. 

3. Facial. 


EFFERENT OR MOTOR. 


Insalivation is the incorporation of the food with the saliva secreted 
by the parotid , sub-maxillary and sub-lingual glands; the parotid saliva, 
thin and watery, is poured into the mouth through Steno’s duct; the sub¬ 
maxillary and sub-lingual salivas, thick and viscid, are poured into the 
mouth through Wharton’s and Bartholini’s ducts. 

In a living serous gland, e.g., parotid, during rest, the secretory cells 
lining the acini of the gland are seen to be filled with fine granules, which 
are often so abundant as to obscure the nucleus and enlarge the cells until 


Fig. i 



Cells of the alveoli of a serous or watery salivary gland. A. After rest. B. After a 
short period of activity. C. After prolonged period of activity .—Front Yeo’s Text- 
Book 0/ Physiology. 

the lumen of the acinus is almost obliterated (Fig. 1). When the gland begins 
to secrete the saliva, the granules disappear from the outer boundary of the 
cells, which then become clear and distinct. At the end of the secretory 
activity, the cells have become free of granules, have become smaller and 
more distinct in outline. It would seem that the granular matter is formed 
in the cells during the rest, and discharged into the ducts during the 
activity of the gland. 

In the mucous glands, e.g., sub-maxillary and sub-lingual, the changes 
that occur in the cells are somewhat different (Fig. 2). During the intervals 
of digestion, the cells lining the gland are large, clear and highly refractive, 
and contain a large quantity of mucigen. After secretion has taken place, 
the cells exhibit a marked change. The mucigen cells have disappeared, 
and in their place are cells which are small, dark and composed of 
protoplasm. It would appear that the cells, during rest, elaborate the 




DIGESTION. 


25 


mucigen which is discharged into the tubules during secretory activity, to 
become part of the secretion. 

Saliva is an opalescent, slightly viscid, alkaline fluid, having a specific 
gravity of 1.005. Microscopical examination reveals the presence of 
salivary corpuscles and epithelial cells. Chemically it is composed of 
water, proteid matter, a ferment {ptyalin) and inorganic salts. The 
amount secreted in 24 hours is about 2^4 lbs. Its function is twofold :— 

1. Physical .—Softens and moistens the food, glues it together, and 
facilitates swallowing. 

2. Chemical .—Converts starch into grape sugar. This action is due to 


Fig. 2. 



Section of a “ mucous ” gland. A. In a state of rest. B. After it has been or some 
time actively secreting .—After Lavdowsky. 


the presence of the organic ferment, ptyalin. The change consists in the 
assumption of a molecule of water. 

Starch. Water. Grape Sugar. 

c 6 H 10 o 5 + h 2 o = c 6 h 12 o 6 . 

NERVOUS CIRCLE OF INSALIVATION. 

AFFERENT OR EXCITOR NERVES. EFFERENT OR MOTOR NERVES. 

1. Lingual branch of 5th pair. 1. Auriculo-temporal branch of 5th 

2. Glosso-pharyngeal. pair, for parotid gland. 

2. Chorda tympani, for sub-maxil¬ 
lary and sub-lingual glands. 

The centres regulating the secretion are two, viz.: The medulla oblon¬ 
gata and the sub-maxillary ganglion of the sympathetic; the latter acting 
antagonistically to the former. Impressions excited by the food in the 
c 


26 


HUMAN PHYSIOLOGY. 


mouth reach the medulla oblongata through the afferent nerves; motor im¬ 
pulses are there generated which pass outward through the efferent nerves. 

Stimulation of the auriculo-temporal branch increases the flow of saliva 
from the parotid gland; division arrests it. 

Stimulation of the chorda tympani is followed by a dilation of the blood 
vessels of the sub-maxillary gland, increased flow of blood (thus acting 
as a vaso-dilator nerve) and an abundant discharge of a thin saliva ; 
division of the nerve arrests the secretion. 

Stimulation of the cervical sympathetic is followed by a contraction of 
the blood vessels, diminishing the flow of blood (thus acting as a vaso¬ 
constrictor nerve) and a diminution of the secretion, which now becomes 
thick and viscid; division of the sympathetic does not, however, completely 
dilate the vessels. There is evidence of the existence of a local vaso¬ 
motor mechanism, which is inhibited by the chorda tympani; exalted by 
the sympathetic. 

Deglutition is the act of transferring food from the mouth into the 
stomach, and may be divided into three stages:— 

1. The passage of the bolus from the mouth into the pharynx. 

2. From the pharynx into the oesophagus. 

3. From the oesophagus into the stomach. 

In the 1st stage , which is entirely voluntary, the mouth is closed and 
respiration momentarily suspended; the tongue, placed against the roof 
of the mouth, arches upward and backward, and forces the bolus into the 
fauces. 

In the 2d stage , which is entirely reflex, the palate is made tense and 
directed upward and backward by the levatores-palati and tensores-palati 
muscles; the bolus is grasped by the superior constrictor muscle of the 
pharynx and rapidly forced into the oesophagus. 

The food is prevented from entering the posterior nares by the uvula 
and the closure of the posterior half-arches (the palato-pharyngei muscles); 
from entering the larynx by its ascent under the base of the tongue and 
the action of the epiglottis. 

In the 3d stage , the longitudinal and circular muscular fibres, contracting 
from above downward, strip the bolus into the stomach. [For nervous 
mechanism of Deglutition, see Medulla Oblongata.] 

Gastric Digestion. The stomach is a dilatation of the alimentary 
canal, 13 inches long, 5 inches deep, having a capacity of about 5 pints; 
there can be distinguished a cardiac and pyloric orifice, a greater and 
lesser curvature, a greater and lesser pouch. 


DIGESTION. 


27 


It possesses three coats:— 

1. Serous, a reflection of the peritoneum. 

2. Muscular, the fibres of which are arranged longitudinally, transversely 
and obliquely. 

3. Mucous, thrown into folds, forming the rugse. 

Imbedded in the mucous coat are immense numbers of mucous and 
true gastric glands. In the pyloric end of the stomach are found the 


Fig. 3. 



Diagram showing the relation of the ultimate twigs of the blood vessels, V and A, and 
of the absorbent radicles to the glands of the stomach and the different kinds of epithe¬ 
lium, viz.,*above cylindrical cells; small, pale cells in the lumen, outside which are the 
dark ovoid cells .—From Veo’s Text-Book 0/ Physiology. 


mucous glands, which are lined with columnar epithelium throughout 
their extent. In the cardiac end are found the true gastric glands 
(Fig. 3), the ducts of which are also lined with columnar cells, while 
the secretory parts are lined with two distinct varieties of cells. One 
variety consists of small, spheroidal, granular cells, which border the 
lumen of the gland, and are known as the chief cells; the other 
variety consists of large, oval, well-defined granular cells, much less 








28 


HUMAN PHYSIOLOGY. 


abundant, and are situated between the basement membrane of the 
gland and the chief cells. From their position they have been termed 
parietal cells. During the intervals of digestion the chief cells are pale, 
and the hyaline substance of which they are composed is finely granular. 
During the stage of active secretion the cells become swollen and turbid, 
and are then said to be rich in pepsin. Toward the end of digestion the 
granules disappear, the cells become pale and return to their former size. 

During the intervals of digestion, the mucous membrane of the stomach 
is pale and covered with a layer of mucus. Upon the introduction of 
food, the blood vessels dilate and become filled with blood, and the 
mucous membrane becomes red. At the same time small drops of a fluid, 
the gastric juice, begin to exude upon its surface, which gradually run 
together and trickle down the sides of the stomach. 

The Gastric Juice is a secretion of the true peptic cells, and when 
obtained from the stomach through a fistulous opening, is a clear, straw- 
colored fluid, decidedly acid, with a specific gravity of 1.005 to 1.010. 

COMPOSITION OF GASTRIC JUICE. 


Water. 975.00 

Pepsin. 1500 

Hydrochloric acid. 4.78 

Inorganic salts. 5.22 


1000.00 

The water forms the largest part of the fluid, and holds in solution the 
other ingredients. It results from a transudation from the blood vessels 
under the increased blood supply. Of the inorganic salts the chlorides of 
sodium and potassium are the most abundant. 

Pepsin is the organic nitrogenized ferment of the gastric juice, and 
is formed, during the intervals of digestion, by the peptic cells. In the 
presence of a small per cent, of an acid, it acquires the property of 
converting the albumen of the food into albuminose or peptones. 

Hydrochloric acid is present in small quantity, and gives the juice its 
acidity. In all probability, its production is due to the activity of the 
parietal cells. 

These two characteristic ingredients of the gastric juice exist in a state 
of combination as hydrochloro-peptic acid, and the presence of both is 
absolutely essential for the complete digestion of the food. When the 
food enters the stomach, it is subjected to the peristaltic action of the 
muscular coat, and thoroughly incorporated with the gastric juice. This 







DIGESTION. 


29 


fluid possesses the property of attacking the connective tissues of the food, 
disintegrating it and dissolving out the alimentary principles. 

The Principal Action of the gastric juice, however, is to transform 
the different albuminous principles of the food into peptones or albuminose , 
the different stages of which are due to the acid and pepsin respectively. 
When freed from its combination, the hydrochloric acid converts the 
albumen into acid albumen or parapeptone\ while this intermediate product 
is being formed, the pepsin converts it at once into peptone. In order that 
the digestion of albumen may be complete, it is necessary that both the 
acid and pepsin be present in proper quantity. Before digestion, the 
albuminous principles are insoluble in water and incapable of being 
absorbed. After digestion, they become soluble and are readily absorbed. 
Peptones differ from the albumins in being— 

1. Diffusible , passing rapidly through the mucous membrane and walls 
of the blood vessels. 

2. Non-coagulable by heat, nitric or acetic acids; but are readily pre¬ 
cipitated by tannic acid, 

3. Soluble in water and saline solutions. 

4. Assimilable by the blood; when injected into it, they do not reappear 
in the urine. 

Gastric juice exerts no influence either upon grape sugar, cane sugar, 
starch or fat. 

Gastric Digestion occupies on the average from 3 to 5 hours, but 
varies in duration according to the nature and quantity of the food, exer¬ 
cise, temperature, etc. 

The Amount of gastric juice secreted in 24 hours varies, under normal 
conditions, from 8 to 14 pounds. 

Movements of the Stomach. As soon as digestion commences, the 
cardiac and pyloric orifices are closed; the walls of the stomach contract 
upon the food, and a peristaltic action begins, which carries the food along 
the greater and lesser curvature#, and thoroughly incorporates it with the 
gastric juice. As soon as any portion of the food is digested, it passes 
through the pylorus into the intestine. 

Vomiting. The act of vomiting is usually preceded by nausea and a 
discharge of saliva into the mouth. This is then swallowed, and carries 
into the stomach a quantity of air which facilitates the ejection of the 
contents of the stomach by aiding the relaxation of the cardiac sphincter. 
A deep inspiration is then taken, during which the lower ribs are drawn 
in and the diaphragm descends and remains contracted. At the same 


30 


HUMAN PHYSIOLOGY. 


time the glottis is closed. A sudden expiratory effort is now made, and 
the cardiac orifice being open, the abdominal muscles contracting, press 
upon the stomach and forcibly eject its contents into the mouth. 

Intestinal Digestion. The intestine is about 20 feet long, 1 ]/ 2 inches 
in diameter, and possesses three coats :— 

1. Serous (peritoneal). 

2. Muscular, the fibres of which are arranged longitudinally and trans- 
versely. 

3. Mucous, thrown into folds, forming the valvulce conniventes. 

This stage of digestion is probably the most complex and important; 
here the different alimentary principles are further elaborated and prepared 


Fig. 4. 



One saccule of the pancreas ot the rabbit in different states of activity. A. After a 
period of rest, in which case the outlines of the cells are indistinct, and the inner zone, 
i. e., the part of the cells (a) next the lumen (c), is broad and filled with fine granules. 
B. After the gland has poured out its secretion, when the cell outlines (d) are clearer, 
the granular zone (a) is smaller, and the clear outer zone is wider .—Freni Yeo's Text- 
Book of Physiology , after Kiihne and Lea. 

for absorption into the blood by being acted upon by the intestinal juice , 
pancreatic juice and bile. 

Throughout the mucous coat are imbedded the intestinal follicles, the 
glands of Brunner and Lieberkvihn. They secrete the true intestinal juice , 
which is an alkaline, viscid fluid, composed of water, organic matter and 
salts. Its function is to convert starch into glucose, and assist in the 
digestion of the albuminoids. 

The Pancreatic Juice is secreted by the pancreas, a flattened gland 
about six inches long, running transversely across the posterior wall of the 
abdomen, behind the stomach; its duct opens into the duodenum. 



DIGESTION. 


31 


The pancreas is similar in structure to the salivary glands, consisting of 
a system of ducts terminating in acini. The acini are tubular or flask¬ 
shaped, and consist of a basement membrane lined by a layer of cylindrical, 
conical cells, which encroach upon the lumen of the acini. The cells 
exhibit a difference in their structure (Fig. 4), and may be said to consist of 
two zones, viz., an outer parietal zone , which is transparent and apparently 
homogeneous, staining readily with carmine; an inner zone , which borders 
the lumen, and is distinctly granular and stains but slightly with carmine. 
These cells undergo changes similar to those exhibited by the cells of the 
salivary glands during and after active secretion. As soon as the secretory 
activity of the pancreas is established, the granules disappear, and the 
inner granular layer becomes reduced to a very narrow border while the 
outer zone increases in size and occupies nearly the entire cell. During 
the intervals of secretion, however, the granular layer reappears and in¬ 
creases in size until the outer zone is reduced to a minimum. It would 
seem that the granular matter is formed by the nutritive processes occurring 
in the gland during rest, and is discharged during secretory activity into 
the ducts and takes part in the formation of the pancreatic secretion. 

The pancreatic juice is transparent, colorless, strongly alkaline and viscid, 
and has a specific gravity of 1.040. It is one of the most important of the 
digestive fluids, as it exerts a transforming influence upon all the classes 
of alimentary principles, and has been shown to contain at least three 
distinct ferments. It has the following composition :— 

COMPOSITION OF PANCREATIC JUICE. 


Water. 900.76 

Albuminoid substances. 90.44 

Inorganic salts. 8.80 


1000.00 

The pancreatic juice is characterized by its action: 1st. Upon starch. 
When starch is subjected to the action of the juice, it is at once transformed 
into glucose; the change takes place more rapidly than when saliva is 
added. This action is caused by the presence of a special ferment, amyl- 
opsin. 2d. Upon albumen. The albuminous bodies are changed by the 
juice into, first, an alkali albumen, and then into peptone. The albumen 
does not swell up, as is the case in gastric digestion, but is gradually cor¬ 
roded and dissolved. This change is due to the presence of the ferment, 
trypsm. Long-continued action of trypsin converts the peptones into two 
crystalline bodies, leucine and tyrosin. 3d. Upon fats. The most striking 
action of the pancreatic juice is the emulsification of the fats or their sub- 






32 


HUMAN PHYSIOLOGY. 


division into minute particles of microscopic size. This change takes place 
rapidly and depends upon the alkalinity of the fluid and the quantity of 
albumen present, combined with the intestinal movements. The neutral 
fats are also decomposed into their corresponding fatty acids and glycerine; 
the acids thus set free unite with the alkaline bases present in the intestine 
and form soaps. This decomposition of the neutral fats is caused by the 
ferment, steapsin. 4th. Upon cane sugar the juice also exerts a special 
influence, converting it readily into glucose. 

The total quantity of this fluid secreted in twenty-four hours has not 
been accurately determined; varies from one to two pounds. It is poured 
out most abundantly an hour after meals. 

The Bile has an important influence in the elaboration of the food and 
its preparation for absorption. It is a golden-brown, viscid fluid, having a 
neutral or slightly alkaline reaction and a specific gravity of 1.020. 

COMPOSITION OF BILB. 


Water. 859.2 

Sodium glycocholate ^ ^ 

Sodium taurocholate / 

Fat. 9.2 

Cholesterine. 2.6 

Mucus and coloring matter. 29.8 

Salts. 7.8 


1000.00 

The Biliary salts, sodium glycocholate and taurocholate, are character¬ 
istic ingredients, and are formed in the liver by the process of secretion, 
from materials furnished by the blood. It is probable that they are derived 
from the nitrogenized compounds, though the stages in the process are 
unknown. They are reabsorbed from the small intestine to play some 
ulterior part in nutrition. 

Cholesterine is a product of waste taken up by the blood from the 
nervous tissues and excreted by the liver. It crystallizes in the form of 
rhombic plates, which are quite transparent. When retained within the 
blood, it gives rise to the condition of cholestercemia, attended with severe 
nervous symptoms. It is given off in the faeces under the form of stercorine. 

The Coloring matters which give the tints to the bile are biliverdin and 
bilirubin , and are probably derived from the coloring matter of the blood. 
Their presence in any fluid can be recognized by adding to it nitric acid 
containing nitrous acid, when a play of colors is observed, beginning with 
green, blue, violet, red and yellow. 









ABSORPTION. 


33 


The Bile is both a secretion and an excretion; it is constantly being 
formed and discharged by the hepatic ducts into the gall bladder, in which 
it is stored up, during the intervals of digestion. As soon as food enters 
the intestines, it is poured out abundantly, by the contraction of the walls 
of the gall bladder. 

The Amount secreted in 24 hours is about 2]/ 2 pounds. 

Functions of the Bile. (1) It assists in the emulsification of the 
fats and promotes their absorption. (2) It tends to prevent putrefactive 
changes in the food. (3) Stimulates the secretions of the intestinal 
glands, and excites the normal peristaltic movements of the bowels. 

The digested food, the chyme , is a grayish, pultaceous mass, but as it 
passes through the intestines it becomes yellow, from admixture with the 
bile. It is propelled onward by vermicular motion; by the contraction of 
the circular and longitudinal muscular fibres. 

As the digested food passes through the intestines, the nutritious 
matters are absorbed into the blood, and the residue enters the large 
intestine. 

The Faeces consist chiefly of indigestible matters, excretin , stercorin 
and salts; varying in amount from 4 to 7 oz. in 24 hours. 

Defecation is the voluntary act of extruding the faeces from the body; 
accomplished by a relaxation of the sphincter muscle, the contraction of 
the walls of the rectum, assisted by the abdominal muscles. 

The Gases contained in the stomach and small intestine are oxygen, 
nitrogen, hydrogen and carbonic acid. In the large intestine, carbonic 
acid, sulphuretted and carburetted hydrogen. They are introduced with 
the food, and also developed by chemical changes in the alimentary canal. 
They distend the intestines, aid capillary circulation, and tend to prevent 
pressure. 

ABSORPTION. 

Absorption has for its object the introduction of new materials into the 
blood, and takes place mainly from the alimentary tract; but also to some 
extent from the skin, respiratory surface and closed cavities of the body. 

The Agents of Absorption are the veins and lymphatics. 

As a result of the process of digestion, the different alimentary substances 
are converted into forms which are capable of being absorbed into the 
blood, e.g., albuminose , glucose and fatty etmilsion, water and inorganic 
matters undergoing no change, being already in a condition to be absorbed 
and to play a part in the nutritive process. 


84 HUMAN PHYSIOLOGY. 

The blood vessels which are most active as absorbents, are the gastric, 
superior and inferior mesenteric veins. They arise in the coats of the 
alimentary canal, and as they converge, unite with the splenic vein to form 
th (t portal vein which enters the liver (Fig. 5). 

As the digested mass of food, the chyme , passes through the alimen¬ 
tary canal, a large portion of it disappears; the veins absorb water, 


Fig. 5- 



Diagram of the portal vein (pv) arising in the alimentary tract and spleen (s), and 
carrying the blood from these organs to the liver .—From Yeo’s Text-Book 0/ Physiology. 

albuminose, glucose, and inorganic salts, and convey them directly 
into the liver; the blood of the portal vein being especially rich in 
these substances. 

At times, after the ingestion of large quantities of oleaginous food, the 
blood vessels take up, in addition, a certain quantity of fatty matter; but 
this is not usually the case; the fats being absorbed by special vessels, the 
lymphatics or lacteals. 


















ABSORPTION. 


35 


General Anatomy of the Lymphatic System. The lymphatics 
constitute a system of minute, delicate, transparent vessels, which, having 
their origin at the periphery of the body, pass forward toward the centre 
and empty into the veins at the base of the neck, by means of the thoracic 
duct. In their course they pass through small ovoid bodies, the lymphatic 
glands. 

Origin of the Lymphatics. The lymphatic vessels arise in several 
distinct ways: i. In lymph spaces or juice canals. Throughout the con¬ 
nective tissues of the body are found numbers of small, irregular, stellate 
spaces, which communicate freely with each other, and represent the 
ultimate radicles of the lymphatic vessels. They frequently contain lymph 
corpuscles. These spaces communicate with the lymph trunks, through the 
medium of the plexuses of lymph capillaries, which are much larger than 
capillary blood vessels, and are lined with endothelial cells with sinuous 
margins. 2. In openings on the surface of serous membranes. The sur¬ 
faces of the serous membranes are covered with a layer of endothelial cells. 
At intervals between these cells are found openings—the stomata. These 
stomata communicate directly, through short canals, with the lymph capil¬ 
laries. The serous cavities may be thus regarded as large lymph spaces. 
3. In perivascular lymph spaces. In the brain and spinal cord the capil¬ 
lary blood vessels are surrounded by a sheath, formed of endothelial cells, 
and which contains lymph. This space is in free communication with the 
lymphatics. By this means the blood vessel is bathed by the lymph stream. 

The lymphatic vessels of the small intestine ( the lacteals) arise within the 
villous processes which project from the inner surface of the intestine 
throughout its entire extent. The wall of the villus is formed by an ele¬ 
vation of the basement membrane, and covered by a layer of columnar 
epithelial cells. The basis of the villus consists of adenoid tissue, fine 
plexus of blood vessels, unstriped muscular fibres and the lacteal vessel. 
The adenoid tissue consists of a number of intercommunicating spaces, 
containing leucocytes. The lacteal vessel possesses a thin, but distinct 
wall, composed of endothelial plates, with here and there openings, which 
bring the interior of the villus into communication with the spaces of the 
adenoid tissue. 

The structure of the larger vessels resembles that of the veins, consisting 
of three coats— 

1. External , composed of fibrous tissue and muscular fibres, arranged 
longitudinally. 2. Middle , consisting of white fibrous and yellow elastic 
tissue, non striated muscular fibres, arranged transversely. 3. Internal , 
composed of an elastic membrane, lined by endothelial cells. 


36 


HUMAN PHYSIOLOGY. 


Throughout their course are found numerous semilunar valves , looking 
toward the larger vessels, formed by a folding of the inner coat and 
strengthened by connective tissue. 

Lymphatic Glands consist of an external fibrous covering, from the 
inner surface of which partitions of fibrous tissue, the trabeculce , pass into 
the substance of the gland, forming a stroma or network, in the meshes of 
which are found the true lymph corpuscles. 

The lymphatics which enter the gland are called the afferent vessels; 
those which leave it, the efferent vessels. 

The Thoracic Duct is the general trunk of the lymphatic system, into 
which the vessels of the lower extremities, of the abdominal organs, of 
the left side of the head and left arm empty their contents. It is about 
twenty inches in length, arises in the abdomen, opposite the third lumbar 
vertebra, by a dilatation, the receptaculum chyli; ascends along the verte¬ 
bral column to the seventh cervical vertebra, and terminates in the venous 
system at the junction of the internal jugular and subclavian veins on the 
left side. The lymphatics of the right side of the head, of the right arm 
and the right side of the thorax, terminate in the right thoracic duct , about 
one inch in length, which joins the venous system at the junction of the 
internal jugular and subclavian on the right side. 

Lymph is a clear, transparent fluid, slightly alkaline, having a saline 
taste and a specific gravity of 1.022. It is found in the lymphatic vessels 
throughout the body. 

Lymph contains a number of corpuscles (the leucocytes ) resembling the 
white corpuscles of the blood, which increase in number as it passes through 
the lymphatic glands. They are about °f an inch in diameter and 
somewhat granular; they are discharged into the blood, but their function 
is obscure. When withdrawn from the vessels, lymph undergoes sponta¬ 
neous coagulation, separating into serum and clot, as in the case of the 
blood. 

COMPOSITION OF LYMPH. 

DR. OWEN REES. 


Water. 96.536 

Proteids (serum-albumen, fibrin, globulin). 1.320 

Extractives (urea, sugar, cholesterine). I -559 

Fatty matter. a trace 

Salts. 0.585 


100.000 

Origin of Lymph. Lymph is undoubtedly a transudation from the 
capillary blood vessels, occurring during the process of nutrition, and is 








ABSORPTION. 


37 



identical, for the most part, with the liquor sanguinis, or plasma. As new 
material is constantly exuded, the old is absorbed by the lymphatics, and 
returned again to the circulation. 

Excrementitious matters, as urea, cholesterine, etc., are also taken up 
from the tissues by the lymphatics and emptied into the blood. 

Fig. 6 . 


Diagram showing the course of the lacteals through the mesentery, and their termina¬ 
tion in the thoracic duct. The course of the thoracic duct and its termination at the 
junction of the internal jugular and subclavian veins. 


The total quantity of lymph poured into the thoracic duct in 24 hours 
has been estimated at y/ 2 lbs. 

Chyle. As a result of the process of digestion, the oleaginous matters 
which have been acted upon by the pancreatic juice and bile are trans- 








38 


HUMAN PHYSIOLOGY. 


formed into a condition of emulsion, forming an opaque, milky fluid, 
termed chyle , which adheres to the folds of the mucous membrane and villi. 

The Molecules of the fat are first absorbed by the epithelial cells 
upon the surface of the villi, through which they pass and enter the 
lymphatics. 

Absorption by the Lacteals. The lacteals , or lymphatics of the 
small intestine, have their origin in the interior of the villi, from which 
they emerge and form a lymphatic plexus; the larger branches of which 
pass through the layers of the mesentery, and finally terminate in the 
thoracic duct (Fig. 6). 

In the intervals of digestion the lacteals contain clear, transparent lymph, 
and are invisible on account of their small size and delicacy. But during 
digestion these vessels become filled, from absorption of the chyle, and 
form a visible network of white vessels ramifying through the mesentery, 
and converging toward the receptaculum chyli. 

The lacteal vessels also absorb a small quantity of water, albuminose, 
glucose and salts. 

COMPOSITION OF CHYLE. 


Water. 902.37 

Albumen. 35.16 

Fibrin. 3.70 

Extractives. 15-65 

Fatty matters. 36.01 

Salts.. 7.11 


1000.00 

The Products of digestion find their way into the general circulation by 
two routes:— 

1. Water, albuminose, glucose and salts are mainly absorbed by the 
gastric and mesenteric veins, carried into the liver, through the capil¬ 
laries* of which they pass, and enter the inferior vena cava by the 
hepatic veins. 

2. The Fats are absorbed by the lacteals, emptied into the thoracic duct, 
and enter the blood at the junction of the internal jugular and subclavian 
veins. 

Forces aiding the movements of Lymph and Chyle. 

1. Endosmosis. The continued transudation of matter from the capil¬ 
laries, and its absorption into the lymphatics by endosmosis, constitutes 
the main cause, the vis-a-tergo, of the movement of the lymph; it is so 
considerable as to rupture the walls of the vessels if they are ligated. 









BLOOD. 


39 


2. Contraction of the non-striated muscular fibres in the walls of the 
lymphatic vessels, especially when fully distended, aided by the action of 
the valves, promotes the onward flow of the fluids. 

3. Muscular contraction in all parts of the body, by exerting intermit¬ 
tent pressure upon the lymphatic vessels, hastens the current onward; 
regurgitation being prevented by the closure of the valves. 

4. The inspiratory movement , by expanding the chest, causes a dilation 
of the thoracic duct, and a rapid flow of lymph and chyle into it; during 
expiration it is compressed, and the fluids forcibly expelled into the venous 
system. 

BLOOD. 

• The Blood is a nutritive fluid containing all the elements necessary for 
the repair of the tissues; it also contains principles of waste absorbed from 
the tissues, which are conveyed to the various excretory organs and by 
them eliminated from the body. 

The total amount of blood in the body is estimated to be about one- 
eighth of the body weight; from 16 to 18 pounds in an individual of 
average physical development. The quantity varies during the 24 hours; 
the maximum being reached in the afternoon, the minimum in the early 
morning hours. 

Blood is a heterogeneous, opaque red fluid, having an alkaline reaction, 
a saline taste, and a specific gravity of 1.055. 

The opacity is due to the refraction of the rays of light by the elements 
of which the blood is composed. The color varies in hue, from a bright 
scarlet in the arteries to a deep purple in the veins, due to the presence of 
a coloring matter, hcemoglobin, in different degrees of oxidation. 

The alkalinity is constant, and depends upon the presence of the alka¬ 
line sodium phosphate, Na 2 H P 0 4 . 

The saline taste is due to the amount of sodium chloride present. 

The specific gravity ranges within the limits of health, from 1.045 to 

1 - 075 - 

The odor of the blood is characteristic, and varies with the animal from 
which it is drawn, due to the presence of caproic acid. 

The temperature of the blood ranges from 98° Fahr. at the surface to 
107° Fahr. in the hepatic vein; it loses heat by radiation and evaporation 
as it approaches the extremities, and as it passes through the lungs. 

Blood consists of two portions :— 

1. The Liquor Sanguinis or Plasma , a transparent, colorless fluid, in 
which are floating— 


40 


HUMAN PHYSIOLOGY. 


2. Red and white corpuscles; these constituting by weight less than 
one-half, 40 per cent., of the entire amount of blood. 


COMPOSITION OF PLASMA. dalton. 

Water. 902.00 

Albumen. 5 3 00 

Paraglobulin. 22.00 

Fibrinogen.v.. 3.00 

Fatty matters. 2.50 

Crystallizable nitrogeneous matters. 4.00 

Other organic matter. 5.00 

Mineral salts. 8.50 


1000.00 

Water acts as a solvent for the inorganic matters and holds in suspen¬ 
sion the corpuscular elements. 

Albumen is the nutritious principle of the blood; it is absorbed by the 
tissues to repair their waste, and is transformed into the organic basis 
characteristic of each structure. 

Paraglobulin or Jibrinoplastin is a soft amorphous substance precipitated 
by sodium chloride in excess, or by passing a stream of carbonic acid 
through dilute serum. 

Fibrinogen can also be obtained by strongly diluting the serum and 
passing carbonic acid through it for a long time, when it is precipitated 
as a viscous deposit. 

Fatty matters exist in small proportion, except in pathological conditions 
and after the ingestion of food rich in oleaginous matters; it soon dis¬ 
appears, undergoing oxidation, generating heat and force, or is deposited ' 
as adipose tissue. 

Sugar is represented by glucose, a product of the digestion of saccharine 
matter and starches in the alimentary canal; glycogenic matter is derived 
from the liver. 

The Saline constituents aid the process of osmosis, give alkalinity to 
the blood, promote the absorption of carbonic acid from the tissues into 
the blood, and hold other substances in solution; the most important are 
the sodium and potassium chlorides, the calcium and magnesium phos¬ 
phates. 

Excrementitious matters are represented by carbonic acid, urea, creatin, 
creatinin, urates, oxalates, etc.; they are absorbed from the tissues by the 
blood and conveyed to the excretory organs, lungs, kidneys, etc. 











BLOOD. 41 

Gases. Oxygen, nitrogen, and carbonic acid exist in varying propor¬ 
tions. 

BLOOD CORPUSCLES. 

The corpuscular elements of the blood occur under two distinct forms, 
which from their color are known as the red and -white corpuscles. 

The Red Corpuscles , as they float in a thin layer of the Liquor Sanguinis, 
are of a pale straw color; it is only when aggregated in masses that they 
assume the bright red color. In form they are circular and biconcave; 
they have an average diameter of the of an inch. 

In mammals, birds, reptiles, amphibia and fish the corpuscles vary in 
size and number, gradually becoming larger and less numerous as the scale 
of animal life is descended, e.g .:— 


TABLE SHOWING COMPARATIVE DIAMETER OF RED 
CORPUSCLES. 


Mammals. 

Birds. 

Reptiles. 

Amphibia. 

Fish. 

Man, 

33W 

Eagle, 

TST3- 

Turtle, jin. 

F ro g, TIS5- 

Perch, 

3000- 

Chimpanzee, 

Owl, 

ITS 3 - 

Tortoise, 3 - 333 . 

Toad, t 343- 

Carp, 

3TIT • 

Ou rang. 

33W 

Sparrow, 

Lizard, tbVs* 

Pro teus, jfo. 

Pike, 

33011 • 

Dog, 

3SJ3- 

Swallow, 5^33. 

Viper, jfa. 

Siren, dfo- 

Eel, 

XT \z- 

Cat, 

44 1 <K* 

Pigeon, rgVs- 


Amphiuma, 3 £ 3 . 



Hog, 

ZESTS' 

Turkey, 





Horse, 

zmv- 

Goose, 

rsW 





Ox, 

zdzr 

Swan, 

TBSB- 






In man and the mammals the red corpuscles present neither a nucleus 
nor a cell wall, and are universally of a small size. They can be readily 
distinguished from the corpuscles of birds, reptiles and fish, in which they 
are larger, oval in shape and possess a well-defined nucleus. 

The red corpuscles are exceedingly numerous, amounting to about 
5,000,000 in a cubic millimetre of blood. In structure they consist of a 
firm, elastic, colorless framework, the stroma, in the meshes of which is 
entangled the coloring matter, the hcemoglobin. 

CHEMICAL COMPOSITION OF RED CORPUSCLES. 


Water. 688.00 

Globulin. 282.22 

Haemoglobin. 16.75 

Fatty matter. 2.31 

Extractives. 2.60 

Mineral salts. 8.12 


1000.00 


D 









42 


HUMAN PHYSIOLOGY. 


Hcemoglobin , the coloring matter of the corpuscles, is an albuminous 
compound, composed of C. O. H. N. S. and iron. It may exist either in 
an amorphous or crystalline form. When deprived of all its oxygen, 
except the quantity entering into its intimate composition, the haemoglobin 
becomes darker in color, somewhat purple in hue, and is known as reduced 
hcemoglobin. When exposed to the action of oxygen, it again absorbs a 
definite amount and becomes scarlet in color, and is known as oxy-hcemo¬ 
globin. The amount of oxygen absorbed is 1.76 c.cm. ( T ^ cubic inch) for 
1 milligramme grain) of haemoglobin. 

It is this substance which gives the color to the venous and arterial 
blood. As the venous blood passes through the capillaries of the lungs, 
the reduced hcemoglobin absorbs the oxygen from the pulmonary air and 
becomes oxy-hcemoglobin, scarlet in color, and the blood becomes arterial. 
When the arterial blood passes into the systemic capillaries, the oxygen 
is absorbed by the tissues, the haemoglobin becomes reduced, purple in 
color, and the blood becomes venous. A dilute solution of oxy-haemo¬ 
globin gives two absorption bands between the lines D and E of the 
solar spectrum. Reduced haemoglobin gives but one absorption band, 
occupying the space existing between the two bands of the oxy-haemo- 
globin spectrum. 

The Function of the red corpuscles is, therefore, to absorb oxygen and 
carry it to the tissues; the smaller the corpuscles, and the greater the 
number, the greater is the quantity of oxygen absorbed; and, consequently, 
all the vital functions of the body become more active. 

The White Corpuscles are far less numerous than the red, the proportion 
being, on an average, about 1 white to 350 or 400 red; they are globular 
in shape, and measure the ffojs °f an diameter, and consist of a 

soft, granular, colorless substance, containing several nuclei. 

The white corpuscles possess the power of spontaneous movement, alter¬ 
nately contracting and expanding, throwing out processes of their substance 
and quickly withdrawing them, thus changing their shape from moment 
to moment. These movements resemble those of the amoeba, and for this 
reason are termed amoeboid. They also possess the capability of moving 
from place to place. In the interior of the vessels they adhere to the inner 
surface, while the red corpuscles move through the centre of the stream. 

The white corpuscles are identical with the leucocytes, and are found 
in milk, lymph, chyle and other fluids. 

Origin of Corpuscles. The red corpuscles take their origin from the 
mesoblastic cells in the vascular area of the developing embryo. 

In the adult they are produced from colorless nucleated corpuscles 


BLOOD. 


43 


resembling the white corpuscles. The spleen is the organ in which they 
are finally destroyed. 

The white corpuscles originate from the leucocytes of the adenoid tissue, 
and subsequently give rise to the red corpuscles and partly to new tissues 
that result from inflammatory action. 


COAGULATION OF THE BLOOD. 

When blood is withdrawn from the body and allowed to remain at rest, 
it becomes somewhat thick and viscid in from three to five minutes; this 
viscidity gradually increases until the entire volume of blood assumes a 
jelly-like consistence, which occupies from five to fifteen minutes. 

As soon as coagulation is completed, a second process begins, which 
consists in the contraction of the coagulum and the oozing of a clear, 
straw-colored liquid, the serum , which gradually increases in quantity as 
the clot diminishes in size, by contraction, until the separation is completed, 
which occupies from 12 to 24 hours. 

The changes in the blood are as follows:— 

Before coagulation. 


I Liq. Sanguinis . 

Living blood, -j or i Consisling of 

Plasma. * 

Corpuscles. Red and white. 

After coagulation. 


Water. 

Albumen. 

Fibrinogen. 

Salts. 


Dead blood. 


' Crassamentum. 1 Containing 
Clot or coagulum. J 

Serum. Containing 


{ 


Fibrin. 

Corpuscles. 

Water. 

Albumen. 

Salts. 


The serum, therefore, differs from the Liquor Sanguinis in not con¬ 
taining fibrin. 

In from 12 to 24 hours the upper surface of the clot presents a grayish 
appearance, the buffy coat , which is due to the rapid sinking of the red 
corpuscles beneath the surface, permitting the fibrin to coagulate without 
them, which then assumes a grayish-yellow tint. Inasmuch as the white 
corpuscles possess a lighter specific gravity than the red, they do not sink 
so rapidly, and becoming entangled in the fibrin, assist in forming the 
buffy coat. Continued contraction gives a cupped appearance to the 
surface of the clot. 





44 


HUMAN PHYSIOLOGY. 


Inflammatory states of the blood produce a marked increase in the 
buffed and cupped condition, on account of the aggregation of the cor¬ 
puscles and their tendency to rapid sinking. 

Nature of Coagulation. Coagulated fibrin does not pre-exist in the 
blood, but is formed at the moment blood is withdrawn from the vessels. 
According to Denis, a liquid substance, plasmine , exists in the blood, 
which, when withdrawn from the circulation, decomposes into fibrin and 
met-albumen. 

According to Schmidt, fibrin results from the union of fibrinoplastin 
(paraglobulin) and fibrinogen , brought about by the presence of a third 
substance, the fibrin ferment. 

According to Hammersten and others, the fibrin obtained from the 
blood after coagulation, comes from the fibrinogen alone, the conversion 
being brought about by the presence of a ferment substance. Paraglobu¬ 
lin in this case having nothing to do with the change. This view is sup¬ 
ported by the fact that the quantity of fibrin obtained from the blood is 
never greater than the quantity of fibrinogen previously present. The 
origin of the ferment is obscure, but there is reason to believe that it comes 
from the injured vascular coats or from the breaking up of the white cor¬ 
puscles. 

Conditions Influencing Coagulation. The process is retarded by 
cold, retention within living vessels, neutral salts in excess, inflammatory 
conditions of the system, imperfect aeration, exclusion from air, etc. 

It is hastened by a temperature of ioo° F., contact with air, rough 
sufaces and rest. 

Blood coagulates in the body after the arrest of the circulation in the 
course of 12 to 24 hours; local arrest of the circulation, from compression 
or a ligature, will cause coagulation, thus preventing hemorrhages from 
wounded vessels. 

The Composition of the Blood varies in different portions of the 
body. The arterial differs from the venous , in being more coagulable, in 
containing more oxygen and less carbonic acid, in having a bright scarlet 
color, from the union of oxygen with haemoglobin; the purple hue of 
venous blood results from the deoxidation of the coloring matter. 

The blood of the portal vein differs in constitution, according to 
different stages of the digestive process; during digestion it is richer in water, 
albuminous matter and sugar; occasionally it contains fat; corpuscles are 
diminished, and there is an absence of biliary substances. 

The blood of the hepatic vein contains a larger proportion of red and 


CIRCULATION OF THE BLOOD. 45 

white corpuscles; the sugar is augmented, while albumen, fat and fibrin 
are diminished. 

Pathological conditions of the Blood. 

1. Plethora —increase in the volume or quantity of blood. 

2. Anaemia —deficiency of red globules with increase of water. 

3. Leucocythemia —increase of white and diminution of red corpuscles. 

4. Glycohcemia —excess of sugar in the blood. 

5. Uraemia —increase in the amount of urea. 

6. Cholestercemia —an excess of cholesterine in the blood. 

7. Thrombosis and embolism —clotting of blood in the vessels and 
dissemination of coagula. 

8. Lipcemia —an excess of fat. 

9. Melancemia —pigment in the blood. 

CIRCULATION OF THE BLOOD. 

The Object of the Circulation is to distribute nutritious blood to 
all portions of the system and to carry waste materials to the various 
eliminating organs. 

The Circulatory Apparatus consists of the heart, arteries, capillaries 
and veins. 

The Heart is a hollow, muscular organ, pyramidal in shape, measuring 
5)/ 2 inches in length and weighing from 10 to 12 oz. in the male, and 8 
to 10 oz. in the female. It is invested externally by a closed fibro-serous 
sac, the pericardium , containing a small amount of fluid, which prevents 
friction as the visceral and parietal layers glide over each other, during 
the movements of the heart and lungs. 

The heart consists of four cavities, a right auricle and ventricle, and a 
left auricle and ventricle, completely separated by a vertical partition. 
The right is the venous side , receiving the blood from the venae cavae, and 
propelling it through the pulmonary artery into the lungs; the left is the 
arterial side , receiving the arterial blood from the lungs by the pulmonary 
veins, and propelling it through the aorta to the system at large. 

The Auriculo-ventricular orifices are guarded on the right and left sides 
by the tricuspid and mitral valves respectively, while they are so arranged 
as to permit the flow of blood in the forward direction only; the orifices 
of th z pulmonary artery and aorta are guarded by the semi-lunar valves. 

The Endocardium is a delicate, shining membrane, lining the interior of 
the heart, and continuous with the lining membrane of the blood vessels. 

The walls of the left ventricle are nearly half an inch in diameter, being 


46 


HUMAN PHYSIOLOGY. 


two or three times thicker than the walls of the right; the force of its 
contraction is, therefore, much greater. 

The Function of the Heart is to propel the blood to all portions of 
the vascular system; accomplished by successive alternate contractions and 
relaxations of its muscular walls, constituting the systole and diastole. 

Course of the blood through the Heart. The venous blood returned 
to the heart by the superior and inferior venae cavae is emptied, during the 
diastole, into the right auricle, on the contraction of which it is forced 
through the right auriculo-ventricular opening into the right ventricle and 
distends it. Upon contraction of the ventricle, the blood is propelled 
through the pulmonary artery into the lungs, where it undergoes aeration 
and is changed in color. 

The arterial blood is now collected by the pulmonary veins and poured 
into the left auricle; thence it passes into the left ventricle, which becomes 
fully distended. Upon the contraction of the ventricle, the blood is pro¬ 
pelled into the aorta, and by it distributed to the system at large, to be 
again returned to the heart by the veins. 

Regurgitation from the ventricles into the auricles during the systole 
is prevented by the closure of the tricuspid and mitral valves; regurgitation 
from the pulmonary artery and aorta into the ventricles during the diastole 
is prevented by the closure of the semi-lunar valves. 

Movements of the Heart. At each revolution, during the systole, 
the heart hardens and becomes shortened in its long diameter; its apex is 
raised up, rotated on its axis from left to right and thrown forward against 
the walls of the chest. The impulse of the heart, observed about two 
inches below the nipple, and one inch to the sternal side, between the fifth 
and sixth ribs, is caused mainly by the apex of the heart striking against 
the chest walls, assisted by the distention of the great vessels about the 
base of the heart. 

Sounds of the Heart. If the ear be placed over the cardiac region, 
two distinct sounds are heard during each revolution of the heart, closely 
following each other and which differ in character. 

The sound coinciding with the systole in point of time, the first sound , 
is long and dull, and caused by the closure and vibration of the auriculo- 
ventricular valves, the contraction of the walls of the ventricles and the 
apex beat; the second sound , occurring during the diastole , is short and 
sharp, and caused by the closure of the semi-lunar valves. 

The capacity of the left ventricle when fully distended is estimated at 
from four to seven ounces. 


CIRCULATION OF THE BLOOD. 


47 


The frequency of the heart’s action varies at different periods of life, 
but in the adult male it beats about 72 times per minute. It is influenced 
by age, exercise, posture, digestion, etc. 

Age. Before birth the number of pulsations per minute averages 140 


During the first year it diminishes to. 128 

During the third year diminishes to. 95 

From the eighth to the fourteenth years averages. 84 

In adult life the average is... 72 


Exercise and digestion increase the frequency of the heart’s action. 

Posture influences the number of pulsations per minute; in the male, 
standing, the average is 81; sitting, 71; lying, 66; independent, for the 
most part, of muscular effort. 

The Rhythmical movements of the heart are dependent upon—1. 
An inherent irritability of the muscular fibre, which manifests itself as long 
as the nutrition is maintained. 2. The continuous flow of blood through 
its cavities distending them and stimulating the endocardium. 

The force exerted by the left ventricle at each contraction has been 
estimated at 52 pounds. If a tube be inserted into the aorta, the pressure 
there will be sufficient to support a column of blood nine feet or a column 
of mercury six inches in height, the weight in either case being about four 
pounds. The estimation of the force which the heart is required to exert 
to support this column of blood, is arrived at by multiplying the pressure 
in the aorta (4 pounds) by the area of the internal surface of the left 
Ventricle (about 13 inches). Each inch of the ventricle being capable of 
supporting a downward pressure of 4 pounds. 

Work done by the Heart. The work done by the heart is estimated 
by multiplying the amount of blood sent out from the right and left 
ventricles at each contraction, by the pressure in the pulmonary artery and 
aorta respectively, e. g., when the right ventricle contracts, it forces out 
one quarter pound of blood, and in so doing must overcome a pressure in 
the pulmonary artery sufficient to support a column of blood three feet in 
height; that is, must exert energy sufficient to raise fib. 3 feet, or X X 3 
or yi lb. one foot. When the left ventricle contracts, it sends out lb. 
of blood, and in so doing, the left ventricle must overcome a pressure in the 
aorta sufficient to support a column of blood nine feet in height; that is 
must exert energy sufficient to raise ^ lb. 9 feet, or X X 9 or fbs. 
one foot. Work done is estimated by the amount of energy required to 
raise a definite weight a definite height, the unit, the foot pound, being 
that required to raise one pound one foot. 






48 


HUMAN PHYSIOLOGY. 


The heart, therefore, at each systole exerts energy sufficient to raise 3 foot 
pounds, and as it contracts 72 times per minute, it would raise in that time 3 
X 72 or 216 foot pounds; and in one hour 216 X 60or 12,960 foot pounds; 
and in 24 hours 12,960 X 2 4 or 3H,°4° foot pounds or 138.5 foot tons. 

Influence of the Nervous System upon the Heart. When the 
heart of a frog is removed from the body, it continues to beat for a variable 
length of time, depending upon the nature of the conditions surrounding 
it. The heart of warm-blooded animals continues to beat but for a very 
short time. The cause of the continued pulsations of the frog heart is the 
presence of nervous ganglia in its substance. These ganglia have not been 
shown to exist in the mammalian heart, but there is reason to believe that 
the nervous mechanism is fundamentally the same. 

The ganglia of the heart are three in number, one situated at the 
opening of the inferior vena cava (the ganglion of Remak), a second 
situated in the auriculo-ventricular septum (the ganglion of Bidder), and 
a third situated in the inter-auricular septum (the ganglion of Ludwig). 
The first two are motor in function and excite the pulsations of the heart; 
the third is inhibitory in function and retards the action of the heart. The 
actions of these ganglia, though for the most part automatic, are modified 
by impressions coming through nerves from the medulla oblongata. When 
the inhibitory centre is stimulated by muscarin, the heart is arrested in 
diastole; when atropia is applied, the heart recommences to beat, because 
atropia paralyzes the inhibitory centre. 

The nerves modifying the action of the heart are the Pneumogastric 
(Vagus) and the Accelerator nerves. 

The Pneumogastric nerve , after emerging from the medulla, receives 
motor fibres from the spinal accessory nerve. It then passes downward, 
giving off branches, some of which terminate in the inhibitory ganglion. 
Stimulation of the vagus by increasing the activity of the inhibitory centre 
arrests the heart in diastole with its cavities full of blood; but as the stimu¬ 
lation is only temporary, after a few seconds the heart recommences to 
beat; at first the pulsations are weak and feeble, but soon regain their 
original vigor. After the administration of atropia in sufficient doses to 
destroy the termination of the pneumogastric, stimulation of its trunk has no 
effect upon the heart. The inhibitory fibres in the vagus are constantly in 
action, for division of the nerve on both sides is always followed by an 
increase in the frequency of the heart’s pulsations. 

The Accelerator fibres arise in the medulla, pass down the cord, emerge 
in the cervical region, pass to the last cervical and first dorsal ganglia of 
the sympathetic, and thence to the heart. Stimulation of these fibres 


ARTERIES. 49 

causes an increased frequency of the heart’s pulsations, but they are di¬ 
minished in force. 


ARTERIES. 

The Arteries are a series of branching tubes conveying blood to all 
portions of the body. They are composed of three coats— 

1. External, formed of areolar and elastic tissue. 

2 . Middle , contains both elastic and muscular fibres, arranged trans¬ 

versely to the long axis of the artery. The elastic tissue is more 
abundant in the larger vessels, the muscular in the smaller. 

3. Internal, composed of a thin homogeneous membrane, covered with 

a layer of elongated endothelial cells. 

The arteries possess both elasticity and contractility. 

The Property of Elasticity allows the arteries already full to accommo¬ 
date themselves to the incoming amount of blood, and to convert the 
intermittent acceleration of blood in the large vessels into a steady and 
continuous stream in the capillaries. 

The Contractility of the smaller vessels equalizes the current of blood, 
regulates the amount going to each part, and promotes the onward flow of 
blood. 

Blood Pressure. Under the influence of the ventricular systole, the 
recoil of the elastic walls of the arteries, and the resistance offered by the 
capillaries, the blood is constantly being subjected to a certain amount of 
pressure. If a large artery of an animal be divided, and a glass tube of 
the same calibre be inserted into its orifice, the blood will rise to a height 
of about nine feet; or if it be connected with a mercurial manometer, the 
mercury will rise to a height of six inches. This height will be a measure 
of the pressure in the vessel. The absolute quantity of mercury sustained 
by an artery can be arrived at by multiplying the height of the column by 
the area of a transverse section of that artery. 

The pressure of the blood is greatest in the large arteries, but gradually 
decreases toward the capillaries. 

The blood pressure is increased or diminished by influences acting upon 
the heart or upon the peripheral resistance of the capillaries, viz.:— 

If, while the force of the heart remains the same, the number of pulsa¬ 
tions per minute increases, thus increasing the volume of blood in the 
arteries, the pressure rises. If the rate remains the same, but the force 
increases, the pressure again rises. Causes that increase the peripheral 
resistance by contracting the arterioles, e. g., vaso-motor nerves, cold, etc., 
produce an increase of the pressure. 


50 


HUMAN PHYSIOLOGY. 


On the other hand, influences which diminish either the volume of the 
blood, or the number of pulsations, or the force of the heart, or the peri¬ 
pheral resistance, lower the pressure. 

The Pulse is the sudden distention of the artery in a transverse and 
longitudinal direction, due to the injection of a volume of blood into the 
arteries at the time of the ventricular systole. As the vessels are already 
full of blood, they must expand in order to accommodate themselves to the 
incoming volume of blood. The blood pressure is thus increased, and the 
pressure originating at the ventricle excites a pulse wave , which passes 
from the heart toward the capillaries at the rate of about twenty-nine feet 
per second. It is this wave that is appreciated by the finger. 

The Velocity with which the blood flows in the arteries diminishes 
from the heart to the capillaries, owing to an increase of the united sec¬ 
tional area of the vessels, and increases in rapidity from the capillaries 
toward the heart. It moves most rapidly in the large vessels, and espe¬ 
cially under the influence of the ventricular systole. From experiments 
on animals, it has been estimated to move in the carotid of man at the rate 
of sixteen inches per second, and in the large veins at the rate of four 
inches per second. 

The Calibre of the blood vessels is regulated by the vaso-motor 
nerves, which have their origin in the gray matter of the medulla oblon¬ 
gata. They issue from the spinal cord through the anterior roots of spinal 
nerves, pass through the sympathetic ganglia, and ultimately are distributed 
to the coats of the blood vessels. They exert, at different times, a constrict¬ 
ing and dilating action upon the vessels, thus keeping up the arterial tonus. 

Capillaries. The capillaries constitute a network of vessels of micro¬ 
scopic size, which distribute the blood to the inmost recesses of the tissues, 
inosculating with the arteries on the one hand and the veins on the other ; 
they branch and communicate in every possible direction. 

The diameter of a capillary vessel varies from the to the °f 
an inch; their walls consist of a delicate homogeneous membrane, the 
-ZjfjfjTG of an inch in thickness, lined by flattened, elongated, endothelial 
cells, between which, here and there, are observed stomata. 

It is through the agency of'the capillary vessels that the phenomena of 
nutrition and secretion takes place, for here the blood flows in an equable 
and continuous current, and is brought into intimate relationship with the 
tissues, two of the essential conditions for proper nutrition. 

The rate of movement in the capillary vessels is estimated at one inch 
in thirty seconds. 


ARTERIES. 


51 


In the capillary current the red corpuscles may be seen hurrying down 
the centre of the stream, while the white corpuscles in the still layer 
adhere to the walls of the vessel, and at times can be seen to pass through 
the walls of the vessel by amoeboid movements. 

The passage of the blood through the capillaries is mainly due to the 
force of the ventricular systole and the elasticity of the arteries; but it is 
probably also aided by a power resident in the capillaries themselves, the 
result of a vital relation between the blood and the tissues. 

The Veins are the vessels which return the blood to the heart; they 
have their origin in the venous radicles, and as they approach the heart, 
converge to form larger trunks, and terminate finally in the venae cavse. 

They possess three coats— 

1. External, made up of areolar tissue. 

2. Middle , composed of non-striated muscular fibres, yellow, elastic and 
fibrous tissue. 

3. Internaly an endothelial membrane, similar to that of the arteries. 

Veins are distinguished by the possession of valves throughout their 

course, which are arranged in pairs, and formed by a reflection of the 
internal coat, strengthened by fibrous tissue; they always look toward the 
heart, and when closed prevent a return of blood in the veins. Valves 
are most numerous in the veins of the extremities, but are entirely absent 
in many others. 

The onward flow of blood in the veins is mainly due to the action of 
the heart; but is assisted by the contraction of the voluntary muscles and 
the force of aspiration. 

Muscular contractiony which is intermittent, aids the flow of blood in 
the veins, by compressing them. As regurgitation is prevented by the 
closure of the valves, the blood is forced onward toward the heart. 

Rhythmical movements of veins have been observed in some of the 
lower animals, aiding the onward current of blood. 

During the movement of inspiration the thorax is enlarged in all its 
diameters, and the pressure on its contents at once diminishes. Under 
these circumstances a suction force is exerted upon the great venous trunks, 
which causes the blood to flow with increased rapidity and volume toward 
the heart. 

Venous pressure. As the force of the heart is nearly expended in 
driving the blood through the capillaries, the pressure in the venous system 
is not very marked, not amounting in the jugular vein of a dog to more 
than that of the carotid artery. 


52 


HUMAN PHYSIOLOGY. 


The time required for a complete circulation of the blood throughout 
the vascular system has been estimated to be from 20 to 30 seconds, while 
for the entire mass of blood to pass through the heart 58 pulsations would 
be required, occupying 48 seconds. 

The Forces keeping the blood in circulation are— 

1. Action of the heart. 

2. Elasticity of the arteries. 

3. Capillary force. 

4. Contraction of the voluntary muscles upon the veins. 

5. Respiratory movements. 


RESPIRATION. 

Respiration is the function by which oxygen is absorbed into the 
blood and carbonic acid exhaled. The appropriation of the oxygen and 
the evolution of carbonic acid takes place in the tissues as a part of the 
general nutritive process; the blood and respiratory apparatus constituting 
the media by means of which the interchange of gases is accomplished. 

The Respiratory Apparatus consists of the larynx, trachea and 
lungs. 

The Larynx is composed of firm cartilages, united together by liga¬ 
ments and muscles; running antero-posteriorly across the upper opening 
are four ligamentous bands, the two superior or false vocal cords, and the 
two inferior or true vocal cords, formed by folds of the mucous membrane. 
They are attached anteriorly to the thyroid cartilages and posteriorly to the 
arytenoid cartilages, and are capable of being separated by the contraction 
of the posterior crico-arytenoid muscles, so as to admit the passage of air 
into and from the lungs. 

The Trachea is a tube from four to five inches in length, three-quarters 
of an inch in diameter, extending from the cricoid cartilage of the larynx 
to the third dorsal vertebra, where it divides into the right and left bronchi. 
It is composed of a series of cartilaginous rings, which extend about two- 
thirds around its circumference, the posterior third being occupied by 
fibrous tissue and non-striated muscular fibres which are capable of dimin¬ 
ishing its calibre. 

The trachea is covered externally by a tough, fibro-elastic membrane, 
and internally by mucous membrane, lined by columnar ciliated epithelial 
cells. The cilia are always waving from within outward. When the two 
bronchi enter the lungs they divide and subdivide into numerous and 


RESPIRATION. 


53 


smaller branches, which penetrate the lung in every direction until they 
finally terminate in the pulmonary lobules. 

As the bronchial tubes become smaller their walls become thinner; the 
cartilaginous rings disappear, but are replaced by irregular angular plates 
of cartilage; when the tube becomes less than the ^ of an inch in di¬ 
ameter they wholly disappear, and the fibrous and mucous coats blend 
together, forming a delicate, elastic membrane, with circular muscular fibres. 

The Lungs occupy the cavity of the 
thorax, are conical in shape, of a pink 
color and a spongy texture. They are 
composed of a great number of distinct 
lobules, the pulmonary lobules, con¬ 
nected together by inter lobular con¬ 
nective tissue. These lobules vary in 
size, are of an oblong shape, and are 
composed of the ultimate ramifications 
of the bronchial tubes, within which are 
contained the air vesicles or cells. The 
walls of the air vesicles, exceedingly 
thin and delicate, are lined internally by 
a layer of tessellated epithelium, exter¬ 
nally covered by elastic fibres, which 
give the lungs their elasticity and dis- 
tensibility. 

The Venous Blood is distributed to 
the lungs for aeration by the pulmonary 
artery, the terminal branches of which 
form a rich plexus of capillary vessels 
surrounding the air cells; the air and 
blood are thus brought into intimate 
relationship, being separated only by the delicate walls of the air cells and 
capillaries. 

The Pleura. Each lung is surrounded by a closed serous membrane, 
the pleura, one layer of which, the visceral, is reflected over the lung, the 
other, the parietal, reflected over the wall of the thorax ; between the two 
layers is a small amount of fluid which prevents friction during the play of 
the lungs in respiration. 

The lungs are nourished by blood from the bronchial arteries ramifying 
in the walls of the bronchial tubes and interlobular connective tissue. 


Fig 7. 



Diagram of the respiratory organs. 
The windpipe leading down from the 
larynx is seen to branch into two large 
bronchi, which subdivide after they 
enter their respective lungs. 






54 


HUMAN PHYSIOLOGY. 


Respiratory movements. The movements of respiration are two, and 
consist of an alternate dilatation and contraction of the chest, known as in¬ 
spiration and expiration. 

1. Inspiration is an active process, the result of the expansion of the 
thorax, whereby air is introduced into the lungs. 

2 . Expiration is a partially passive process, the result of the recoil of 
the elastic walls of the thorax, and the recoil of the elastic tissue of the 
lungs, whereby the carbonic acid is expelled. 

In Inspiration the chest is enlarged by an increase in all its diameters, 
viz.:— 

1. The vertical is increased by the contraction and descent of the dia¬ 
phragm when it approximates a straight line. 

2. The anteroposterior and transverse diameters are increased by the 
elevation and rotation of the ribs upon their axes. 

In ordinary tranquil inspiration the muscles which elevate the ribs and 
thrust the sternum forward, and so increase the diameters of the chest, are 
the external intercostals , running from above downward and forward, the 
sternalportion of the internal intercostals and the levatores costarum. 

In the extraordinary efforts of inspiration certain auxiliary muscles are 
brought into play, viz.; the sterno-mastoid , perforates, serratus magnus , 
which increase the capacity of the thorax to its utmost limit. 

In Expiration the diameters of the chest are all diminished, viz.: 

1. The vertical , by the ascent of the diaphragm. 

2. The anteroposterior , by a depression of the ribs and sternum. 

In ordinary tranquil expiration the diameters of the thorax are dimin¬ 
ished by the recoil of the elastic tissue of the lungs and the ribs; but in 
forcible expiration the muscles which depress the ribs and sternum, and 
thus further diminish the diameter of the chest, are the internal inter - 
costals, the infracostals , and the triangularis sterni. 

In the extraordinary efforts of expiration certain auxiliary muscles are 
brought into play, viz.: the abdominal and sacro-lumbalis muscles , which 
diminish the capacity of the thorax to its utmost limit. 

Expiration is aided by the recoil of the elastic tissue of the lungs and 
ribs and the pressure of the air. 

Movements of the Glottis. At each inspiration the rima glottidis is 
dilated by a separation of the vocal cords, produced by the contraction of 
the crico arytenoid muscles, so as to freely admit the passage of air into the 
lungs; in expiration they fall passively together, but do not interfere with 
the exit of the air from the chest. 


RESPIRATION. 


55 


Nervous Mechanism of Respiration. The movements of respira¬ 
tion are involuntary and reflex, and are under the control of the medulla 
oblongata. 

This centre may be stimulated— 

1. Directly , by the condition of the blood. An increase of carbonic acid 
or a diminution of oxygen in the blood causes an acceleration of the 
respiratory movements; the reverse of these conditions causes a diminu¬ 
tion of the respiratory movements. 

2. Indirectly , by reflex action. The medulla' may be excited to action 
through the pneumogastric nerve, by the presence of carbonic acid in the 
lungs irritating its terminal filaments; through the fifth nerve, by irrita¬ 
tion of the terminal branches; and through the nerves of general sensibility. 
In either case this centre reflects motor impulses to the respiratory muscles 
through the phrenic , intercostals, inferior laryngeal and other nerves. 

Types of Respiration. The abdominal type is most marked in young 
children, irrespective of sex ; the respiratory movements being effected by 
the diaphragm and abdominal muscles. 

In the superior costal type , exhibited by the adult female, the respiratory 
movements are more marked in the upper part of the chest, from the 1st 
to the 7th ribs, permitting the uterus to ascend in the abdomen during 
pregnancy without interfering with respiration. 

In the inferior costal type , manifested by the male, the movements are 
largely produced by the muscles of the lower portion of the chest, from the 
7th rib downward, assisted by the diaphragm. 

The respiratory movements vary according to age, sleep and exercise, 
being most frequent in early life, but averaging 20 per minute in adult life. 
They are diminished by sleep and increased by exercise. There are about 
four pulsations of the heart to each respiratory act. 

During inspiration two sounds are produced; the one, heard in the 
thorax, in the trachea and larger bronchial tubes, is tubular in character; 
the other, heard in the substance of the lungs, is vesicular in character. 

AMOUNT OF AIR EXCHANGED IN RESPIRATION, AND CAPACITY 

OF LUNGS. 

The Tidal or breathing volume of air, that which passes in and out of 
the lungs at each inspiration and expiration, is estimated at from 20 to 30 
cubic inches. 

The Complemental air is that amount which can be taken into the lungs 
by a forced inspiration, in addition to the ordinary tidal volume, and 
amounts to about no cubic inches. 


56 


HUMAN PHYSIOLOGY. 


The Reserve air is that which usually remains in the chest after the 
ordinary efforts of expiration, but which can be expelled by forcible expira¬ 
tion. The volume of reserve air is about ioo cubic inches. 

The Residual air is that portion which remains in the chest and cannot 
be expelled after the most forcible expiratory efforts, and which amounts, 
according to Dr. Hutchinson, to about ioo cubic inches. 

The Vital Capacity of the chest indicates the amount of air that can 
be forcibly expelled from the lungs after the deepest possible inspiration, 
and is an index of an individual’s power of breathing in disease and pro¬ 
longed severe exercise. The combined amounts of the tidal, the comple- 
mental and reserve air, 230 cubic inches, represents the vital capacity of an 
individual 5 feet 7 inches in height. The vital capacity varies chiefly with 
stature. It is increased 8 cubic inches for every inch in height above this 
standard, and diminishes 8 cubic inches for each inch below it. 

The Tidal Volume of air is carried only into the trachea and larger 
bronchial tubes by the inspiratory movements. It reaches the deeper 
portions of the lungs in obedience to the law of diffusion of gases, which 
is inversely proportionate to the square root of their densities. 

The ciliary action of the columnar cells lining the bronchial tubes also 
assists in the interchange of air and carbonic acid. 

The entire volume of air passing in and out of the thorax in 24 hours is 
subject to great variation, but can be readily estimated from the tidal 
volume and the number of respirations per minute. Assuming that an 
individual takes into the chest 20 cubic inches at each inspiration, and 
breathes 18 times per minute, in 24 hours there would pass in and out of 
the lungs 518,400 cubic inches or 300 cubic feet. 

Composition of Air: Oxygen, 20.81 parts; nitrogen, 79.19, forming a 
mechanical mixture in which exist traces of carbonic acid and watery 
vapor. 

The changes in the air effected by respiration are— 

Loss of oxygen, to the extent of 5 cubic inches per 100 of air, or 1 in 
20. * 

Gain of carbonic acid, to the extent of 4.66 cubic inches per 100 of 
air or .93 inch in 20. 

Increase of watery vapor and organic matter. 

Elevation of temperature. 

Increase and at times decrease of nitrogen. 

Gain of ammonia. 

The total quantity of oxygen withdrawn from the air and consumed by 


RESPIRATION. 


57 


the body in 24 hours amounts to 15 cubic feet, and can be readily esti¬ 
mated from the amount consumed at each respiration. Assuming that one 
inch of oxygen remains in the lungs at each respiration, in one hour there 
are consumed 18 inches, and in 24 hours, 25,920 cubic inches or 15 cubic 
feet, weighing 18 oz. To obtain this quantity, 300 cubic feet of air are 
necessary. 

The quantity of carbonic acid exhaled in 24 hours varies greatly. It 
can be estimated in the same way. Assuming that an individual exhales 
•93 + cubic inch at each respiration, in one hour there are eliminated 1008 
cubic inches, and in 24 hours 24,192 cubic inches or 14 cubic feet, con¬ 
taining 7 oz. of pure carbon. 

As oxygen and carbon unite to form an equal volume of carbonic acid 
gas, there disappears daily in the body, one cubic foot of oxygen, which 
in all probability unites with the surplus hydrogen of the food to form 
water. 

The exhalation of carbonic acid is increased by muscular exercise; 
nitrogenous food; tea, coffee and rice; age, and by muscular develop¬ 
ment ; decreased by a lowering of temperature; repose; gin and brandy, 
and a dry condition of the air. 

Condition of the Gases in the Blood. 

Oxygen is absorbed from the lungs into the arterial blood by the coloring 
matter, hcemoglobin , with which it exists in a state of loose combination, 
and is disengaged during the process of nutrition. 

Carbonic acid , arising in the tissues, is absorbed into the blood, in conse¬ 
quence of its alkalinity; where it exists in a state of simple solution and 
also in a state of feeble combination with the carbonates, soda and potassa, 
forming the bicarbonates; it is liberated bypneumic acid in the pulmonary 
tissue. 

Nitrogen is simply held in solution in the plasma. 

The amount of watery vapor thrown off from the lungs daily is about 
one pound, with which is mingled organic matter and ammonia. 

Changes in the Blood during Respiration. 

As the blood passes through the lungs it is changed in color , from 
the dark purple hue of venous blood to the bright scarlet of arterial 
blood. 

The heterogeneous composition of venous blood is exchanged for the 
uniform composition of the arterial. 

It gains oxygen and loses carbonic acid. 

Its coagulability is increased. Temperature is diminished. 

E 


58 


HUMAN PHYSIOLOGY. 


Asphyxia. If the supply of oxygen to the lungs be diminished and 
the carbonic acid retained in the blood, the normal respiratory move¬ 
ments cease, the condition of asphyxia ensues, which soon terminates 
in death. 

The phenomena of asphyxia are, violent spasmodic action of the respi¬ 
ratory muscles, attended by convulsions of the muscles of the extremities, 
engorgement of the venous system, lividity of the skin, abolition of sensi¬ 
bility and reflex action, and death. 

The cause of death is a paralysis of the heart, from over distention by 
blood. The passage of the blood through the capillaries is prevented by 
contraction of the smaller arteries, from irritation of the vaso-motor centre. 
The heart is enfeebled by a want of oxygen and inhibited in its action by 
the inhibitory centres. 

ANIMAL HEAT. 

The Functional Activity of all the organs and tissues of the body is 
attended by the evolution of heat, which is independent, for the most part, 
of external conditions. Heat is a necessary condition for the due perform¬ 
ance of all vital actions; though the body constantly loses heat by radia¬ 
tion and evaporation , it possesses the capability of renewing it and main¬ 
taining it at a fixed standard. The normal temperature of the body in the 
adult, as shown by means of a delicate thermometer placed in the axilla, 
ranges from 97.25 0 Fahr. to 99.5 0 Fahr., though the mean normal tem¬ 
perature is estimated by Wunderlich at 98.6° Fahr. 

The temperature varies in different portions of the body, according to 
the degree in which oxidation takes place; being the highest in the muscles 
during exercise, in the brain, blood, liver, etc. 

The conditions which produce variations in the normal temperature 
of the body are: age, period of the day, exercise, food and drink, climate, 
season and disease. 

Age. At birth the temperature of the infant is about i° F. above that 
of the adult, but in a few hours falls to 95.5 0 F., to be followed in the 
course of 24 hours by a rise to the normal or a degree beyond. During 
childhood the temperature approaches that of the adult; in aged persons 
the temperature remains about the same, though they are not as capable 
of resisting the depressing effects of external cold as adults. A diurnal 
variation of the temperature occurs from i.8° F. to 3.6° F. (Jiirgensen); 
the maximum occurring late in the afternoon, from 4 to 9 p.m., the mini¬ 
mum, early in the morning, from 1 to 7 A.M. 

Exercise. The temperature is raised from i° to 2° F. during active 


ANIMAL HEAT. 


69 


contractions of the muscular masses, and is probably due to the increased 
activity of chemical changes; a rise beyond this point being prevented by 
its diffusion to the surface, consequent on a more rapid circulation, radia¬ 
tion, more rapid breathing, etc. 

Food and drink. The ingestion of a hearty meal increases the tempera¬ 
ture but slightly; an absence of food, as in starvation, produces a marked 
decrease. Alcoholic drinks, in large amounts, in persons unaccustomed 
to their use, cause a depression of the temperature, amounting from i° to 
2° F. Tea causes a slight elevation. 

External temperature. Long continued exposure to cold, especially 
if the body is at rest, diminishes the temperature from i° to 2° F., while 
exposure to a great heat slightly increases it. 

Disease frequently causes a marked variation in the normal temperature 
of the body, rising as high as 107° F. in typhoid fever, and 105° F. in pneu¬ 
monia ; in cholera it falls as low as 8o° F. Death usually occurs when the 
heat remains high and persistent, from 106° to 110 °F.; the increase of heat 
in disease is due to excessive production rather than to diminished elimina¬ 
tion. 

The source of heat is to be sought for in the chemical combinations 
taking place during the general process of nutrition, and the amount of 
its production is in proportion to the activity of the internal changes. 

Every contraction of a muscle, every act of secretion, each exhibition 
of nerve force, is accompanied by a change in the chemical composition of 
the tissues and an evolution of heat. The reduction of the disintegrated 
tissues to their simplest form by oxidation ; the combination of the oxygen 
of the inspired air with the carbon and hydrogen of the blood and tissues, 
results in the formation of carbonic acid and water and the generation of a 
large amount of heat. 

Certain elements of the food, particularly the non-nitrogenized sub¬ 
stances, undergo oxidation without taking part in the formation of the 
tissues, being transformed into carbonic acid and water, and thus increase 
the sum of heat in the body. 

Heat-producing Tissues. All the tissues of the body add to the 
general amount of heat, according to the degree of their activity. But 
special structures, on account of their mass and the large amount of blood 
they receive, are particularly to be regarded as heat producers ; e. g :— 

1. During mental activity the brain receives nearly one-fifth of the 
entire volume of blood, and the venous blood returning from it is charged 
with waste matters, and its temperature is increased. 


60 


HUMAN PHYSIOLOGY. 


2. The muscular tissue , on account of the many chemical changes 
occurring during active contractions, must be regarded as the chief heat- 
producing tissue. 

3. The secreting glands , during their functional activity, add largely to 
the amount of heat. 

Of the entire quantity of heat generated in the body, it is estimated 
that only a small proportion is utilized, as five-sixths escape by radiation 
and evaporation, the remaining one-sixth being utilized in keeping the 
body at the normal temperature standard, 98.6° F., and in the production 
of muscular force. 

The body loses heat by radiation and evaporation from the general 
cutaneous surface, the respiratory passages and by the urine and fceces. 
About 75 per cent, of all the heat lost escapes from the skin. In passing 
through the lungs the temperature of the blood is lowered by about 
1° Fahr. 

The nervous system influences the production of heat in a part, by 
increasing the amount of blood going through it by its action upon the 
vaso-motor nerves. Whether there exists a special heat centre has not 
been satisfactorily determined, though this is probable. 


SECRETION. 

The Process of Secretion consists in the separation of materials from 
the blood, which are either to be again utilized to fulfill some special pur¬ 
pose in the economy, or are to be removed from the body as excrementi- 
tious matter; in the former case they constitute the secretions , in the latter, 
the excretions. 

The materials which enter into the composition of the secretions are 
derived from the nutritive principles of the blood, and require special 
organs, e. g., gastric glands, mammary glands, etc., for their proper 
elaboration. 

The materials which compose the excretions pre-exist in the blood, and 
are the results of the activities of the nutritive process; if retained within 
the body they exert a deleterious influence upon the composition of the 
blood. 

Destruction of a secreting gland abolishes the secretion peculiar to it, 
and it cannot be formed by any other gland; but among the excreting 
organs there exists a complementary relation, so that if the function of one 
organ be interfered with, another performs it, to a certain extent. 


SECRETION. 


61 


CLASSIFICATION OF THE SECRETIONS. 

PERMANENT FLUIDS. 

Serous fluids. Vitreous humor of the eye. 

Synovial fluid. Fluid of the labyrinth of the internal 

Aqueous humor of the eye. ear. 

Cerebro-spinal fluid. 


TRANSITORY FLUIDS. 

Gastric juice. 

Pancreatic juice. 

Secretion from Brunner’s glands. 
Secretion from Leiberkuhn’s glands. 
Secretion from follicles of the large 
intestine. 

Bile (also an excretion). 

EXCRETIONS. 

Perspiration and the secretion of Urine. 

the axillary glands. Bile (also a secretion). 


Mucus. 

Sebaceous matter. 

Cerumen (external meatus). 
Meibomian fluid. 

Milk and colostrum. 

Tears. 

Saliva. 


FLUIDS CONTAINING FORMED ANATOMICAL ELEMENTS. 

Seminal fluid, containing spermatozoids. Fluid of the Graafian follicles. 

The essential apparatus for secretion is a delicate, homogeneous, 
structureless membrane , on one side of which, in close contact, is a capil¬ 
lary plexus of blood vessels , and on the other side a layer of cells whose 
physiological function varies in different situations. 

Secreting organs may be divided into membranes and glands. 

Serous membranes usually exist as closed sacs, the inner surface of which 
is covered by pale, nucleated epithelium, containing a small amount of 
secretion. 

The serous membranes are the pleura, peritoneum, pericardium, synovial 
sacs, etc. 

The serous fluids are of a pale amber color, somewhat viscid, alkaline, 
coagulable by heat, and resemble the serum of the blood; their amount 
is but small; the pleural varies from 4 to 7 drachms; the peritoneal from 
1 to 4 ounces; the pericardial from 1 to 3 drachms. 

The synovial fluid is colorless, alkaline, and extremely viscid, from the 
presence of synovine. 

The function of serous fluids is to moisten the opposing surfaces, so as 
to prevent friction during the play of the viscera. 

The mucous membranes are soft and velvety in character, and line the 
cavities and passages leading to the exterior of the body, e. g., the gastro 


62 


HUMAN PHYSIOLOGY. 


intestinal , pulmonary and genito-urinary. They consist of a primary 
basement membrane covered with epithelial cells, which, in some situa¬ 
tions, are tessellated, in others, columnar. 

Mucus is a pale, semi-transparent, alkaline fluid, containing epithelial 
cells and leucocytes.. It is composed, chemically, of water, an albumin¬ 
ous principle, mucosine, and mineral salts; the principal varieties are 
nasal, bronchial, vaginal and urinary. 

Secreting Glands are formed of the same elements as the secreting 
membranes; but instead of presenting flat surfaces, are involuted, forming 
tubules, which may be simple follicles, e. g., mucous, uterine or intestinal; 
or compound follicles, e. g., gastric glands, mammary glands; or racemose 
glands, e. g., salivary glands and pancreas. They are composed of a 
basement membrane, enveloped by a plexus of blood vessels, and are 
lined by epithelial and true secreting cells, which in different glands possess 
the capability of elaborating elements characteristic of their secretions. 

In the production of the secretions two essentially different pro¬ 
cesses are concerned:— 

1. Chemical. The formation and elaboration of the characteristic organic 
ingredients of the secreting fluids, e. g., pepsin, pancreatin, takes place 
during the intervals of glandular activity, as a part of the general func¬ 
tion of nutrition. They are formed by the cells lining the glands, and can 
often be seen in their interior with the aid of the microscope, e. g., bile in 
the liver cells, fat in the cells of the mammary gland. 

2 . Physical. Consisting of a transudation of w'ater and mineral salts 
from the blood into the interior of the gland. 

During the intervals of glandular activity, only that amount of blood 
passes through the gland sufficient for proper nutrition; when the gland 
begins to secrete, under the influence of an appropriate stimulus, the blood 
vessels dilate and the quantity of blood becomes greatly increased beyond 
that flowing through the gland during its repose. 

Under these conditions a transudation of water and salts takes place, 
washing out the characteristic ingredients, which are discharged by the 
gland ducts. The discharge of the secretions is intermittent; they are 
retained in the glands until they receive the appropriate stimulus, when 
they pass into the larger ducts by the vis-a-tergo, and are then discharged 
by the contraction of the muscular walls of the ducts. 

The activity of glandular secretion is hastened by an increase in the 
blood pressure and retarded by a diminution. 

The nervous centres in the medulla oblongata influence secretion, (i) by 


MILK. 


63 


increasing or diminishing the amount of blood entering a gland; (2) by 
exerting a direct influence upon the secreting cells themselves, the centres 
being excited by reflex irritation, mental emotion, etc. 

MAMMARY GLANDS. 

The Mammary Glands secrete the milk, and undergo at different 
periods of life remarkable changes in structure. Though rudimentary in 
childhood, they gradually increase in size as the young female approaches 
puberty. 

The gland presents, at its convexity, a small prominence of skin, the 
nipple, surrounded by an areola of a deeper tint. It is covered anteriorly 
by a layer of adipose tissue and posteriorly by a fibrous structure which 
attaches it loosely to the pectoralis muscle. 

During utero-gestation the mammae become large, firm, well-developed 
and lobulated ; the areola becomes darker and the veins more prominent. 
In the intervals of lactation the glands gradually shrink in size to their 
original condition, undergo involution, and become non-secreting organs. 

Structure of the Mammae. The mamma is a conglomerate gland, 
consisting of a number of lobes, from 15 to 20 in number, each of which is 
subdivided into lobules made up of gland vesicles or acini. The ducts 
which convey the secretion to the exterior, the lactiferous ducts, open by 
15 to 20 orifices upon the surface of the nipple, at the base of which they 
are dilated to form little reservoirs in which the milk collects during the 
periods of active secretion. 

The walls of the lacteal duct consist of white, fibrous tissue, and non- 
striated muscular fibres, lined by short columnar cells, which disappear 
during active lactation. The ducts measure about the j 1 ^ of an inch in 
diameter; as they pass into the substance of the gland, each duct divides 
into a number of branches, which are distributed to distinct lobules and 
terminate in the acini. 

An acinus is made up of a number of vesicles composed of a homoge¬ 
neous membrane, lined by pavement epithelium. The gland vesicles are 
held together by white, fibrous tissue, which unites the lobules into lobes. 

MILK. 

Milk has a pale, blue color, is almost inodorous, of a sweetish taste, an 
alkaline reaction, and a specific gravity varying from 1.025 t0 LCtyiS. 
Examined microscopically it is seen to contain an immense number of 
globules, measuring the of an inch in diameter, suspended in a clear 


64 


HUMAN PHYSIOLOGY. 


fluid; these are the milk globules , formed of a small mass of oily matter 
covered by a layer of albumen. 

The quantity of milk secreted by the human female in 24 hours, during 
the period of lactation, is about two to three pints; the quantity removed 
by the infant from a full breast at one time being about two ounces. 


COMPOSITION OF MILK. 

Water. 890.00 

Proteids, including casein and serum albumen. 35 .oo 

Fatty matter (butter). 25.00 

Sugar (lactose) with extractives. 48.00 

Salts. . 2.00 


1000.00 

Casein is the nutritive principle of milk, and constitutes its most import¬ 
ant ingredient. It is held in solution by an alkali, but upon the addition 
of an acid it undergoes coagulation, passing into a semi-solid form. The 
presence of lactic acid, resulting from a transformation of milk sugar, 
causes spontaneous coagulation to take place. 

The Fatty matter is more or less solid at ordinary temperature, and con¬ 
sists of margarine and oleine; when subjected to the churning process the 
globules run together and form a coherent mass, the butter. 

When milk is allowed to stand for a varying length of time the fat glob¬ 
ules rise to the surface, forming a layer more or less thick, the cream. 

Milk sugar or lactose is an important ingredient in the food of the young 
child; it is readily transformed into lactic acid in the presence of nitro- 
genized ferments. 

Influences modifying the secretion. During lactation there is a 
demand for an increased amount of fluid, and if not supplied, the amount 
of milk secreted is diminished. Good food in sufficient quantity is neces¬ 
sary for the proper elaboration of milk, though no particular article influ¬ 
ences its production. 

Mental emotion at times influences the character of the milk, decreasing 
the amount of its different constituents. 

Mechanism of Secretion. The water and salts pre-exist in the blood 
and pass into the gland vesicles by osmosis. The casein, fatty matter and 
sugar appear only in the mammary gland, but the mechanism of their for¬ 
mation is not understood. 

Colostrum is a yellowish, opaque fluid, formed in the mammary glands 
towards the latter period of utero-gestation; it consists of water, albumen, 
fat, sugar and salts, and acts as a laxative to the newly-born infant. 








VASCULAR OR DUCTLESS GLANDS. 


65 


VASCULAR OR DUCTLESS GLANDS. 

The Vascular Glands are regarded as possessing the power of acting 
upon certain elements of the food and aiding the process of sanguinifi- 
cation; of modifying the composition of the blood as it flows through their 
substance, by some act of secretion. 

The vascular glands are the spleen , suprarenal capsules , thyroid and 
thymus glands. 

The Spleen is about 5 inches in length, 6 ounces in weight, of a dark 
bluish color, and situated in the left hypochondriac region. It is covered 
externally by a reflection of the peritoneum, beneath which is the proper 
fibrous coat, composed of areolar and elastic tissue and non-striated 
muscular fibres. From the inner surface of the fibrous envelope processes 
or trabeculae are given off, which penetrate the substance of the gland, 
forming a network, in the meshes of which is contained the splee 7 i pulp. 
The splenic artery divides into a number of branches, some of which, 
when they become very minute, pass directly into veins, while others 
terminate in true capillaries. 

As the capillary vessels ramify through the substance of the gland, their 
walls frequently disappear and the blood passes from the arteries into the 
veins through lacunce (Gray). 

The splenic or Malpighian corpuscles are small bodies, spherical or ovoid 
in shape, the -fa of an inch in diameter, situated upon the sheaths of the 
small arteries. They consist of a delicate membrane, containing a semi¬ 
fluid substance composed of numerous small cells resembling lymph cor¬ 
puscles. The spleen pulp is a dark red, semi-fluid substance, of a soft 
consistence, contained in the meshes of the trabeculae. In it are found 
numerous corpuscles, like those observed in the Malpighian bodies, blood 
corpuscles in a natural and altered condition, nuclei and pigment granules. 

Function of the Spleen. Probably influences the preparation of the 
albuminous food for nutrition; during digestion the spleen becomes larger, 
its contents are increased in amount, and after digestion it gradually dimin¬ 
ishes in size, returning to the normal condition. 

The red corpuscles are here disintegrated, after having fulfilled their 
function in the blood; the splenic venous blood containing relatively a 
small quantity. 

The white coipuscles appear to be increased in number, the blo&d of the 
splenic vein containing an unusually large proportion. 

The spleen serves also as a reservoir for blood when the portal circula¬ 
tion becomes obstructed. 


66 


HUMAN PHYSIOLOGY. 


The nervous system controls the enlargement of the spleen; division of 
the nerve produces dilatation of the vessels, stimulation contracts them. 

The Supra-renal Capsules are triangular, flattened bodies, situated 
above the kidney. They are invested by a fibrous capsule sending in 
trabeculae, forming the framework. The glandular tissue is composed of 
two portions, a cortical and medullary. The cortical being made up of 
small cylinders lined by cells and containing an opaque mass, nuclei and 
granular matter. The medullary consists of a fibrous network containing 
in the alveoli nucleated protoplasm. 

The Thyroid gland consists of a fibrous stroma, containing ovoid 
closed sacs, measuring on the average ^ of an inch, formed of a delicate 
membrane lined by cells; the contents of the sacs consist of yellowish 
albuminous fluid. 

The Thymus gland is most developed in early life and almost disap¬ 
pears in the adult. It is divided by processes of fibrous tissue into lobules, 
and these again into follicles which contain lymphoid corpuscles. 

The functions of the vascular glands appear to be the more complete 
elaboration of the blood necessary for proper nutrition; they are most 
highly developed during infancy and embryonic life, when growth and 
development are most active. 

EXCRETION. 

The Principal Excrementitious Fluids discharged from the body 
are the urine, perspiration and bile; they hold in solution principles of 
waste which are generated during the activity of the nutritive process, and 
are the ultimate forms to which the organic constituents are reduced in 
the body. They also contain inorganic salts. 

The Urinary Apparatus consists of the kidneys, ureters and bladder. 

KIDNEYS. 

The Kidneys are the organs for the excretion of urine; they resemble 
a bean in shape, are from four to five inches in length, two in breadth, 
and weigh from four to six ounces. 

They are situated in the lumbar region, one on each side of the vertebral 
column, tfehind the peritoneum, and extend from the nth rib to the crest 
of the ilium; the anterior surface is convex, the posterior concave, and 
presents a deep notch, the hilum. 

The kidney is surrounded by a thick layer of fat, beneath which is the 


KIDNEYS. 


67 


fibrous coat, thin and smooth, composed of dense white fibrous tissue with 
which are intermingled elastic fibres. It is adherent to the surface of the 
organ, but can easily be removed by dissection. 


Fig. 8. 



Longitudinal section through the kidney, the pelvis of the kidney, and a number of 
renal calyces. A, branch of the renal artery; U, ureter; C, renal calix; i, cortex; i', 
medullary rays; i", labyrinth, or cortex proper; 2, medulla; 2', papillary portion of 
medulla, or medulla proper; 2'', border layer of the medulla; 3, 3, transverse section 
through the axes of the tubules of the border layer; 4, fat of the renal sinus; 5, 5, arterial 
branches; *, transversely coursing medulla rays.— Tyson, after Henle. 

The Substance of the Kidney is dense, but friable; upon making 
a longitudinal section, and dividing it, there is presented a cavity, the 



s 







68 


HUMAN PHYSIOLOGY. 


pelvis , lined by the proper fibrous coat and occupied by the expanded 
portion of the ureter. 

The kidney exhibits two structures, viz.: — 

1. An external ox cortical portion, about l /e of an inch in diameter, of 
a reddish color, and somewhat granular. 

2 . An internal or medullary portion, of a dark red color, arranged in 
the form of pyramids , the bases of which are directed toward the cortical 
portion, and the apices toward the pelvis, into which they project, and are 
covered by the calyces. 

The Cortical portion of the kidney consists of a delicate matrix con¬ 
taining an immense number of tubules, having a markedly convoluted 
appearance, and interlacing in every direction (the tubules of Ferrein). 
Throughout its structure are numerous ovoid bodies, the Malpighian 
bodies , which are the flask-like terminations of the convoluted tubules; 


Fig. 9. 



Diagrammatic exposition of the method in which the uriniferous tubes unite to form 
primitive cones.— Tyson, after Ludwig. 

these tubes are composed of a delicate homogeneous membrane lined by 
nucleated cells. After pursuing a most intricate course in the cortical 
portion, they become narrower and form loops which dip into the pyra¬ 
midal portion (Henle’s tubules), returning upon themselves, to finally 
terminate in the straight tubes of the pyramids. 

The Malpighian bodies, the dilated extremities of the convoluted 
tubes, consist of a little sac (the capsule of Muller), which is ovoid in 
shape, measuring about the of an inch in diameter, and contains a 
tufted mass of minute blood vessels,, over the surface of which is reflected 
a layer of cells. 

Medullary Substance. The conical masses, the pyramids of Mal¬ 
pighi, consist of a number of straight tubes, which commence at the apex 
by from 10 to 20 openings; and as they pass toward the cortical portion } 
they divide and subdivide at acute angles, until a large mass of tubes is 






KIDNEYS. 


69 


produced. These tubes are on the average about jfo of an inch in 
diameter, and composed of a thin, but firm, elastic, structureless mem¬ 
brane, lined by polygonal nucleated cells, which reduce the diameter 
of the lumen of the tube about two-thirds; these are th e. straight tubes 
of Bellini. 

Blood vessels of the Kidney. The renal artery is of large size and 
enters the organ at the hilum; it divides into several large branches, 
which penetrate the substance of the kidney, between the pyramids, at the 
base of which they form an anastomosing plexus, which completely sur¬ 
rounds them. From this plexus vessels follow the straight tubes toward 
the apex, while others entering the cortical portion, divide into small twigs 
which enter the Malpighian body and form a mass of convoluted vessels, 
the glomerulus. After circulating through the Malpighian tuft the blood 
is gathered together by two or three small veins, which again subdivide 
and form a fine capillary plexus, which envelops the convoluted tubules; 
from this plexus the veins converge to form the emulgent vein, which 
empties into the vena cava. 

The nerves of the kidney follow the course of the blood vessels and 
are derived from the renal plexus. 

The Ureter is a membranous tube, situated behind the peritoneum, 
about the diameter of a goose quill, 18 inches in length, and extends from 
the pelvis of the kidney to the base of the bladder, which it perforates in 
an oblique direction. It is composed of 3 coats, fibrous, muscular and 
mucous. 

The Bladder is a temporary reservoir for the reception of the urine 
prior to its expulsion from the body; when fully distended it is ovoid in 
shape, and holds about one pint. It is composed of four coats, serous, 
muscular , the fibres of which are arranged longitudinally and circularly, 
areolar and mucous. The orifice of the bladder is controlled by the 
sphincter vesica, a muscular band, about half an inch in width. 

As soon as the urine is formed it passes through the tubuli tirinifei'i 
into the pelvis, and from thence through the ureters into the bladder, which 
it enters at an irregular rate. Shortly after a meal, after the ingestion of 
large quantities of fluid, and after exercise, the urine flows into the bladder 
quite rapidly, while it is reduced to a few drops during the intervals of 
digestion. It is prevented from regurgitating into the ureters on account 
of the oblique direction they take between the mucous and muscular 
coats. 


70 


HUMAN PHYSIOLOGY. 


Nervous Mechanism of Urination. When the urine has passed into 
the bladder it is there retained by the sphincter vesicse muscle kept in a 
state of tonic contraction by the action of a nerve centre in the lumbar 
region of the spinal cord. This centre can be inhibited and the sphincter 
relaxed, either reflexly, by impressions coming through sensory nerves from 
the mucous membrane of the bladder, or directly , by a voluntary impulse 
descending the spinal cord. When the desire to urinate is experienced, 
impressions made upon the vesical sensory nerves are carried to the centres 
governing the sphincter and detrusor urince muscles and to the brain. If 
now the act of urination is to take place, a voluntary impulse, originating 
in the brain, passes down the spinal cord and still further inhibits the 
sphincter vesicae centre, with the effect of relaxing the muscle, and of 
stimulating the centre governing the detrusor muscle, with the effect of con¬ 
tracting the muscle and expelling the urine. If the act is to be suppressed 
voluntary impulses inhibit the detrusor centre and possibly stimulate the 
sphincter centre. 

The genito-spinal centre controlling these movements is situated in that 
portion of the spinal cord corresponding to the origin of the 3d, 4th and 
5th sacral nerves. 

URINE. 

Normal Urine is of a pale yellow or amber color, perfectly transparent, 
with an aromatic odor, an acid reaction, a specific gravity of 1.020, and a 
temperature when first discharged of ioo° Fahr. 

The color varies considerably in health, from a pale yellow to a brown 
hue, due to the presence of the coloring matter, urobilin or urochrome. 

The transparency is diminished by the presence of mucus, the calcium 
and magnesium phosphates and the mixed urates. 

The reaction is slightly acid, caused by the acid phosphate of sodium. 
After standing for a short time, an increased acidity is observed, due 
to an acid fermentation, from the presence of mucus. The urea is 
converted into ammonium carbonate, giving rise to a strong ammoniacal 
odor. 

The specific gravity varies from 1.010 to 1.025. 

The quantity of urine excreted in 24 hours is between 40 and 50 fluid 
ounces, but ranges above and below this standard. 

The odor is characteristic, and caused by the presence of taurylic and 
phenylic acids, but is influenced by vegetable foods and other substances 
eliminated by the kidneys. 


URINE. 


71 


COMPOSITION OF URINE. 

Water... 

Urea. 

Other nitrogenized crystalline bodies, uric acid, prin¬ 
cipally in the form of alkaline urates. 

Creatin, creatinin, xanthin, hypoxanthin. 

Hippuric acid, leucin, tyrosin, taurin, cystin, all in 
small amounts, and not constant. 

Mucus and pigment. 

Salts:— 

Inorganic, principally sodium and potassium sulphates, 
phosphates and chlorides, with magnesium and cal¬ 
cium phosphates, traces of silicates and chlorides. 

Organic: lactates, hippurates, acetates, formates, 
which appear only occasionally. 

Sugar. 

Gases (nitrogen and carbonic acid principally). 


967. 

14.230 


10.635 


8.135 


a trace. 


1000.00 

The Average Quantity of the principal constituents excreted in 24 


hours is as follows:— 

Water.. 52 fluid oz. 

Urea. 512.4 grains.. 

Uric acid. 8.5 “ 

Phosphoric acid. 45.0 “ 

Sulphuric acid. 31.11 “ 

Inorganic salts. 323.25 “ 

Lime and magnesia. 6.5 “ 


To Determine the amount of solid matters in any given amount of 
urine, multiply the last two figures of the specific gravity by the coefficient 
of Hseser, 2.33; e. g ., in 1000 grains of urine having a specific gravity 
1.022, there are contained 22 X 2 *33 = 51.26 grains of solid matter. 

The Elimination of the urinary constituents is accomplished by the 
two processes of filtration and secretion. 

1. By Filtration the water and mineral salts are removed from the 
blood, and takes place, for the most part, in the Malpighian corpuscles, 
by the process of osmosis. The amount of these constituents eliminated 
varies with the pressure of blood in the renal arteries. All of the agencies 
which increase the general blood pressure increase the quantity of urine. 

Season. In summer, while the capillary vessels of the skin are dilated, 















72 


HUMAN PHYSIOLOGY. 


and perspiration is abundant, there is a diminished blood pressure, and a 
consequent diminution in the amount of urine; in winter the reverse takes 
place. 

During sleep the renal excretion is diminished, but increased in the 
morning hours, and especially after the ingestion of hearty meals. 

The nervous system influences the secretion of urine. Irritation of the 
medulla oblongata, a little above the origin of the pneumogastric and 
auditory nerves, increases the quantity; division of the renal nerves 
destroys the nutrition of the kidney, and thus interferes with the elimina¬ 
tion of the urine. Mental emotion, fear, anxiety, etc., increase the amount 
secreted. 

2. Secretion. While it is established that the Malpighian corpuscles 
permit the filtration of water and salts, it has also been shown that the 
renal epithelial cells lining the convoluted tubes are the agencies by which 
the solid matters, urea , creatin , etc., are removed from the blood, by a 
process of true secretion, which is independent of blood pressure and 
caused by the pressure of these ingredients in the blood. 

Urea is the most important of the organic constituents of the urine. It 
is a colorless, neutral substance, crystallizing in four-sided prisms, soluble 
in boiling alcohol and water; when subjected to prolonged boiling it is 
decomposed, with the production of ammonium carbonate. 

Urea is not formed in the kidneys, but pre-exists in the blood. 

The Amount of Urea excreted in 24 hours is estimated at about 500 
grains; it is increased during the waking hours, by an animal diet, and 
by prolonged muscular exertion; diminished during sleep and by non- 
nitrogenized food. 

Source. Urea results from an imperfect oxidation of the albuminous 
principles of the food, and from a disintegration of the organic constituents 
of the tissues. 

Uric acid, or lithic acid, is a constant ingredient of the urine; the 
amount excreted daily is about 8 grains; it is increased by nitrogenized, 
decreased by non-nitrogenized food. It exists in the urine in a free state, 
and as the urate of soda. It arises from the disassimilation of albuminous 
compounds, and when secreted in excess is deposited in a crystalline form, 
as a brown or “brick-red” sediment, with the sodium and ammonium 
urates. 

Creatin is a colorless, transparent substance, crystallizing in prisms; 
found in blood, kidneys, and muscular tissue; by boiling in acid solutions 
it is transformed into 


LIVER. 


73 





Creatinin, which resembles creatin chemically. It is soluble in water 
and alcohol, and crystallizes in colorless prisms. About 15 grains are 
excreted daily. 

The Earthy phosphates are insoluble in water but held in solution in 
the urine by the acid reaction. If the urine becomes alkaline, they are 
deposited copiously, and yet may not be increased in quantity; from 15 to 
25 grains are excreted in 24 hours. The stilphates are those of sodium 
and potassium; they are very soluble and do not appear as a precipitate; 
the average quantity excreted in 24 hours is about 60 grains. 

Abnormal ingredients appear in the urine at times, in pathological con¬ 
ditions, e. g., sugar, albumen, biliary salts, etc. 

The Gases of the urine are carbonic acid and nitrogen. 

LIVER. 

The Liver is a highly vascular, conglomerate gland, appended to the 
alimentary canal, and performs the triple office of (1) excreting bile, (2) 
elaborating blood and (3) secreting glycogen. 

It is the largest gland in the body, weighing about 4^ pounds; it is 
situated in the right hypochondriac region, and retained in position by five 
ligaments, four of which are formed by duplicatures of the peritoneal in¬ 
vestment. 

The proper coat of the liver is a thin but firm fibrous membrane, closely 
adherent to the surface of the organ, which it penetrates at the transverse 
fissure, and follows the vessels in their ramifications through its substance, 
constituting Glisson's capsule. 

Structure of the Liver. The liver is made up of a large number of 
small bodies, the lobules, rounded or ovoid in shape, measuring the ^ of 
an inch in diameter, separated by a space in which are situated blood 
vessels, nerves, hepatic ducts and lymphatics. 

The lobules are composed of cells, which, when examined microscopi. 
cally, exhibit a rounded or polygonal shape, and measure, on the aver¬ 
age, the jjVh °f an * nc h diameter; they possess one, and at times two, 
nuclei; they also contain globules of fat, pigment matter, and animal 
starch. The cells constitute the secreting structure of the liver, and are the 
true hepatic cells. 

The Blood vessels which enter the liver are (1) The portal vein, 
made up of the gastric, splenic, superior and inferior mesenteric veins ; 
(2) the hepatic artery, a branch of the coeliac axis; both of which are 
invested by a sheath of areolar tissue; the vessels which leave the liver 


F 


74 


HUMAN PHYSIOLOGY. 


are the hepatic veins, originating in its interior, collecting the blood dis¬ 
tributed by the portal vein and hepatic artery, and conducting it to the 

ascending vena cava. 

Distribution of Vessels. The portal vein and hepatic artery, upon 
entering the liver, penetrate its substance, divide into smaller and smaller 
branches, occupy the spaces between the lobules, completely surrounding 
and limiting them, and constitute the inter-lobular vessels. The hepatic 
artery, in its course, gives off branches to the walls of the portal vein and 
Glisson’s capsule, and finally empties into the small branches of the portal 
vein in the interlobular spaces. 

The interlobular vessels form a rich plexus around the lobules, from 
which branches pass to neighboring lobules and enter their substance, 
where they form a very fine network of capillary vessels, ramifying 
over the hepatic cells, in which the various functions of the liver are 
performed. The blood is then collected by small veins, converging to¬ 
ward the centre of the lobule, to form the intra-lobular vein, which runs 
through its long axis and empties into the sub-lobular vein. The hepatic 
veins are formed by the union of the sub-lobular veins, and carry the 
blood to the ascending vena cava; their walls are thin and adherent to the 
substance of the hepatic tissue. 

The Hepatic Ducts or Bile Capillaries originate within the lobules, 
in a very fine plexus lying between the hepatic cells; whether the smallest 
vessels have distinct membranous walls, or whether they originate in the 
spaces between the cells by open orifices, has not been satisfactorily deter¬ 
mined. 

The Bile Channels empty into the interlobular ducts, which measure 
about ■zJ-q-q of an inch in diameter, and are composed of a thin homo¬ 
geneous membrane lined by flattened epithelial cells. 

As the interlobular bile ducts unite to form larger trunks, they receive 
an external coat of fibrous tissue, which strengthens their walls; they 
finally unite to form one large duct, the hepatic duct, which joins the cystic 
duct; the union of the two forms the ductus communis choledochus, which 
is about three inches in length, the size of a goose quill, and opens into 
the duodenum. 

The Gall Bladder is a pear-shaped sack, about four inches in length, 
situated in a fossa on the under surface of the liver. It is a reservoir for 
the bile, and is capable of holding about one ounce and a half of fluid. It 
is composed of three coats, (i) serous, a reflection of the peritoneum, (2) 
fibrous and muscular, (3) mucous. 


LIVER. 


75 


(1) Bile. Mechanism of its Secretion. Bile does not preexist in 
the blood, but is formed in the interior of the hepatic cells, from materials 
derived from the venous as well as arterial blood. The secreted bile is 
then taken up by the delicate plexus of vessels, from which it passes into 
the larger ducts, and finally either empties into the intestine or is regur¬ 
gitated backward into the gall bladder, in which it is stored up during the 
intervals of digestion. 

Although the secretion of bile is constantly taking place, it is only when 
the food passes into the intestinal canal that this fluid is discharged abund¬ 
antly, under the influence of the contraction of the walls of the gall 
bladder; it increases in amount during the period of active digestion, from 
the 2d to the 8th hour, and then gradually diminishes. 

The Bile is both a secretion and an excretion; it contains new con¬ 
stituents which are formed only in the substance of the liver, and are 
destined to play an important part ultimately in nutrition; it contains also 
waste ingredients which are discharged into the intestinal canal and 
eliminated from the body. 

The physical properties and functions of bile have been considered 
under the head of digestion (see page 32). 

(2) Elaboration of Blood. Besides the capability of secreting bile, the 
liver possesses the property of so acting upon and modifying the chemical 
composition of the products of digestion, as they traverse its substance, that 
they readily assimilate with the blood, and are transformed into materials 
capable of being converted into the elements of the blood and solid tissues. 

The albuminose particularly requires the modifying influence of the 
liver; for if it be removed from the portal vein and introduced into the 
jugular vein, it is at once removed from the blood by the action of the 
kidneys. 

The blood of the hepatic vein differs from the blood of the portal vein , 
in being richer in blood corpuscles, both red and white; its plasma is 
more dense, containing a less percentage of water and a greater amount 
of solid constituents, but no fibrin; its serum contains less albumen, fat and 
salts, but its sugar is increased. 

(3) Glycogenic Function. In addition to the two preceding func¬ 
tions, Bernard, in 1848, demonstrated the fact that the liver, during life, 
normally produces a sugar-forming substance, analogous in its chemical 
composition to starch, which he termed glycogen; also that when the liver 
is removed from the body, and its blood vessels thoroughly washed out, 
after a few hours, sugar again makes its appearance, in abundance. 


76 


HUMAN PHYSIOLOGY. 


It can be shown to exist in the blood of the hepatic vein as well as in 
a decoction of the liver substance, by means of either Trommer’s or 
Fehling’s tests, even when the blood of the portal vein does not contain a 
trace of sugar. 

Origin and Destination of Glycogen. Glycogen appears to be 
formed de novo in the liver cells, from materials derived from the food, 
whether the diet be animal or vegetable, though a larger per cent, is 
formed when the animal is fed on starchy and saccharine, than when fed 
on animal food. The glucose , which is one of the products of digestion, 
is absorbed by the blood vessels, and carried directly into the liver; as it 
does not appear in the urine, as it would if injected at once into the general 
circulation, it is probable that it is detained in the liver, dehydrated and 
stored up as glycogen. The change is shown by the following formula: — 
Glucose. Water. Glycogen. 

C 6 H 12°6 — H 2° = C 6 H 10°5- 

The glycogen thus formed is stored up in the hepatic cells for the 
future requirements of the system. When it is carried from the liver it is 
again transformed into glucose by the agency of a ferment. Glycogen 
does not undergo oxidation in the blood; this takes place in the tissues, 
particularly in the muscles, where it generates heat and contributes to the 
development of muscular force. 

Glycogen, when obtained from the liver, is an amorphous, starch-like 
substance, of a white color, tasteless and odorless, and soluble in water; 
by boiling with dilute acids, or subjected to the action of an animal 
ferment, it is easily converted into glucose. When an excess of sugar is 
generated by the liver, it can be found, not only in the blood of the hepatic 
vein, but also in other portions of the body; under these circumstances 
it is eliminated by the kidneys, appearing in the urine, constituting the 
condition of glycosuria. 

The nervous system influences the production of the glycogenic 
matter; irritation of the medulla oblongata, between the auditory and 
pneumogastric nerves, is followed by an increase in the production of 
sugar, and its appearance in the urine, which, however, is only temporary. 

SKIN. 

The Skin, the external investment of the body, is a most complex and 
important structure, serving (i) as a protective covering; (2) an organ for 
tactile sensibility; (3) an organ for the elimination of excrementitious 
matters. 


APPENDAGES OF THE SKIN. 


77 


The Amount of Skin investing the body of a man of average size is 
about twenty feet, and varies in thickness, in different situations, from the 
x /% to the of an inch. 

The skin consists of two principal layers, viz., a deeper portion, the 
Corium, and a superficial portion, the Epidermis. 

The Corium, or Cutis Vera, may be subdivided into a reticulated and 
a papillary layer. The former is composed of white fibrous tissue, non- 
striated muscular fibres and elastic tissue, interwoven in every direction, 
forming an areolar network, in the meshes of which are deposited masses 
of fat, and a structureless amorphous matter; the latter is formed mainly of 
club-shaped elevations or projections of the amorphous matter, constituting 
th t papilla; they are most abundant, and well developed, upon the palms 
of the hands and the soles of the feet; they average the of an inch 
in length, and may be simple or compound; they are well supplied with 
nerves, blood vessels and lymphatics. 

The Epidermis or scarf skin is an extra-vascular structure, a product 
of the true skin, and composed of several layers of cells. It may be 
divided into two layers, the rete mucosum or the Malpighian layer , and 
the horny or corneous. 

The former closely applies itself to the papillary layer of the true skin, 
and is composed of large, nucleated cells, the lowest layer of which, the 
“prickle cells,” contain pigment granules, which give to the skin its 
varying tints in different individuals and in different races of men; the 
more superficial cells are large, colorless, and semi-transparent. The 
latter , the corneous layer, is composed of flattened cells, which, from their 
exposure to the atmosphere, are hard and horny in texture; it varies in 
thickness from ^ °f an inch on the palms of the hands and feet, to the 
of an inch in the external auditory canal. 

APPENDAGES OF THE SKIN. 

Hairs are found in almost all portions of the body, and can be divided 
into (i) long, soft hairs, on the head; (2) short, stiff hairs, along the edges 
of the eyelids and nostrils; (3) soft, downy hairs, on the general cutane¬ 
ous surface. They consist of a root and a shaft , which is oval in shape, 
and about the of an inch in diameter; it consists of fibrous tissue, 
covered externally by a layer of imbricated cells, and internally by cells 
containing granular and pigment material. 

The Root of the hair is embedded in the hair follicle, formed by a tubular 
depression of the skin, extending nearly through to the subcutaneous tissue; 


78 


HUMAN PHYSIOLOGY. 


its walls are formed by the layers of the corium, covered by epidermic 
cells. At the bottom of the follicle is a papillary projection of amorphous 
matter, corresponding to a papilla of the true skin, containing blood vessels 
and nerves, upon which the hair root rests. The investments of the hair 
roots are formed of epithelial cells, constituting the internal and external 
root sheaths. 

The hair protects the head from the heat of the sun and cold, retains 
the heat of the body, prevents the entrance of foreign matter into the lungs, 
nose, ears, etc. The color is due to the pigment matter, which, in old age, 
becomes more or less whitened. 

The Sebaceous Glands, imbedded in the true skin, are simple and 
compound racemose glands, opening, by a common excretory duct, upon 
the surface of the epidermis or into the hair follicle. They are found in 
all portions of the body, most abundantly in the face, and are formed by a 
delicate, structureless membrane, lined by flattened polyhedral cells. The 
sebaceous glands secrete a peculiar oily matter, the sebum , by which the 
skin is lubricated and the hairs softened; it is quite abundant in the region 
of the nose and forehead, which often present a greasy, glistening appear¬ 
ance; it consists of water, mineral salts, fatty globules, and epithelial cells. 

The Vernix caseosa which frequently covers the surface of the foetus at 
birth consists of the residue of the sebaceous matters, containing epithelial 
cells and fatty matters; it seems to keep the skin soft and supple, and 
guards it from the effects of the long continued action of water. 

The Sudoriparous Glands excrete the sweat; they consist of a mass 
or coil of a tubular gland duct, situated in the derma and in the sub¬ 
cutaneous tissue; average the ^ of an inch in diameter, and are surrounded 
by a rich plexus of capillary blood vessels. From this coil the duct passes 
in a straight direction up through the skin to the epidermis, where it makes 
a few spiral turns and opens obliquely upon the surface. The sweat 
glands consist of a delicate homogeneous membrane lined by epithelial 
cells, whose function is to extract from the blood the elements existing in 
the perspiration. 

The glands are very abundant all over the cutaneous surface, as many 
as 3528 to the square inch, according to Erasmus Wilson. 

The Perspiration is an excrementitious fluid, clear, colorless, almost 
odorless, slightly acid in reaction, with a specific gravity of 1.003 or 1-004. 

The total quantity of perspiration excreted daily has been estimated 
at about two pounds, though the amount varies with the nature of the food 
and drink, exercise, external temperature, season, etc. 


PERSPIRATION. 


79 


The elimination of the sweat is not intermittent, but continuous; but 
it takes place so gradually that as fast as it is formed it passes off by 
evaporation as insensible perspiration. Under exposure to great heat and 
exercise the evaporation is not sufficiently rapid, and it appears as sensible 
perspiration. 

COMPOSITION OF SWEAT. 


Water.. 995-573 

Urea. 0.043 

Fatty matters. 0.014 

Alkaline lactates. 0.317 

Alkaline sudorates. 1.562 

Inorganic salts. 2.491 


1000.000 

Urea is a constant ingredient. 

Carbonic acid is also exhaled from the skin, the amount being about 
of that from the lungs. 

Perspiration regulates the temperature, and removes waste matters from 
the blood ; it is so important, that if elimination be prevented death occurs 
in a short time. 

The Nervous System influences the secretion of watery vapor by causing 
a dilatation of the capillary blood vessels around the tubular coil. It is 
increased by mental emotions; section of the sympathetic fibres in the 
neck is followed by a copious perspiration; stimulation of the nerves, pro¬ 
ducing contraction of the vessels, is followed by an arrestation of the 
elimination of the sweat. 









80 


HUMAN PHYSIOLOGY. 


NERVOUS SYSTEM. 

The Nervous System co-ordinates all the various organs and tissues 
of the body, and brings the individual into conscious relationship with 
external nature by means of sensation, motion, language, mental and moral 
manifestations. 

The Nervous Tissue may be divided into two systems, viz: the 
Cerebrospinal and the Sympathetic. 

(1) The Cerebro-spinal System occupies the cavities of the cranium 
and spinal canal, and consists of the brain, the spinal cord, the cranial and 
spinal nerves. It is the system of animal life, and presides over the func¬ 
tions of sensation, motion, etc. 

(2) The Sympathetic System, situated along each side of the spinal 
column, consists (1) of a double chain of ganglia, united together by nerve 
cords, which extends from the base of the cranium to the coccyx; (2) of 
various ganglia, situated in the head and face, thorax, abdomen, pelvis, 
etc. All the ganglia are united together by numerous communicating 
fibres, many of which anastomose with the fibres of the cerebro-spinal 
system. It is the nervous system of organic life, and governs the functions 
of nutrition, growth, etc. 

Nervous Tissue is composed of two kinds of matter, the gray and 
white , which differ in their color, structure and physiological endowments; 
the former consists of vesicles or cells which receive and generate nerve 
force; the latter consists of fibres which simply conduct it, either from the 
periphery to the centre or the reverse. 

Structure of Gray Matter. The gray matter, found on the surface of 
the brain in the convolutions, in the interior of the spinal cord, and in the 
various ganglia of the cerebro-spinal and sympathetic nervous systems, 
consists of a fine connective-tissue stroma, the neuroglia , in the meshes of 
which are embedded the gray cells or vesicles. 

The cells are grayish in color, and consist of a delicate investing cap¬ 
sule containing a soft, granular, albuminous matter, a nucleus , and some¬ 
times a nucleolus. Some of the cells are spherical or oval in shape, while 
others have an interrupted outline, on account of having one, two, or more 
processes issuing from them, constituting the uni-polar , bi-polar or multi¬ 
polar nerve cells. Cells vary in size; the smallest being found in the brain, 
the largest in the anterior horns of gray matter of the spinal cord. Some of 


NERVOUS SYSTEM. 


81 


the cell processes become continuous with the fibres of the white matter, 
while others anastomose with those of adjoining cells and form a plexus. 

Structure of the White Matter. The white matter, found for the 
most part in the interior of the brain, on the surface of the spinal cord, and 
in almost all the nerves of the cerebro-spinal and sympathetic systems, 
consists of minute tubules or fibres, the ultimate nerve filaments, which 
in the perfectly fresh condition, are apparently structureless and homoge¬ 
neous; but when carefully examined after death are seen to consist of three 
distinct portions, (i) a tubular membrane; (2) the white substance of 
Schwann; (3) the axis cylinder. 

The Tubular membrane, investing the nerve filament, is thin, homo¬ 
geneous, and lined by large, oval nuclei, and presents, in its course, annu¬ 
lar constrictions; it serves to keep the internal parts of the fibre in position, 
and protects them from injury. 

The White substance of Schwann, or the medullary layer, is situated 
immediately within the tubular membrane, and gives to the nerves their 
peculiar white and glistening appearance. It is composed of oleaginous 
matter in a more or less fluid condition; after death it undergoes coagula¬ 
tion, giving to the fibre a knotted or varicose appearance. It serves to 
insulate the axis cylinder, and prevents the diffusion of the nerve force. 

The Axis cylinder occupies the centre of the medullary substance. In 
the natural condition it is transparent and invisible, but when treated with 
proper reagents, it presents itself as a pale, granular, flattened band, 
albuminous in character, more or less solid, and somewhat elastic. It is 
composed of a number of minute fibrillse united together to form a single 
bundle. (Schultze.) 

Nerve fibres in which these three structural elements coexist are known 
as the medullated nerve fibres. In the sympathetic system, and in the 
gray substance of the cerebro-spinal system, many nerves are destitute of a 
medullary layer, and are known as the non-?nedullated nerve fibres. 

Gray or Gelatinous nerve fibres, found principally in the sympathetic 
system, are gray in color, semi-transparent, flattened, with distinct borders, 
finely granular, and present oval nuclei. 

The diameter of the gelatinous fibres is about the an of 

the medullated fibres, from to of an inch. 

Ganglia are small bodies, varying considerably in size, situated on the 
posterior roots of spinal nerves, on the sensory cranial nerves, alongside 
of the vertebral column, forming a connected chain, and in the different 
viscera. They consist of a dense, investing, fibrous membrane, containing 


82 


HUMAN PHYSIOLOGY. 


in its interior gray or vesicular cells, among which are found white and gela¬ 
tinous nerve fibres. They may be regarded as independent nerve centres. 

Structures of Nerves. Nerves are rounded or flattened cords extend¬ 
ing from the centres to the periphery; they are surrounded externally by 
a sheath, the neurilemma , composed of fibrous and elastic tissue forming 
a stroma, in which blood vessels ramify, from which the nerves derive 
their nourishment. 

A Nerve consists of a greater or less number of ultimate nerve filaments , 
separated into bundles by fibrous septa, given off from the neurilemma. The 
nerve filaments pursue an uninterrupted course, from their origin to their 
termination; branches pass from one nerve trunk into the sheath of another, 
but there is no anastomosis or coalescence with adjoining nerve fibres. 

A Plexus is formed by a number of branches of different nerves inter¬ 
lacing in every direction, in the most intricate manner, but from which 
fibres are again given off to pursue their independent course, e. g., brachial, 
cervical, lumbar, sacral, cardiac plexuses, etc. 

SPINAL NERVES. 

Origin. The spinal nerves are thirty-one in number on each side of 
the spinal cord, and arise by two roots, an anterior and posterior , from the 
anterior and posterior aspects of the cord respectively; the posterior roots 
present near their emergence from the cord a small ganglionic enlargement; 
outside of the spinal canal the two roots unite to form a main trunk, which 
is ultimately distributed to the skin, muscles and viscera. 

The Function of the Anterior Roots is to transmit motor impulses 
from the centres outward to the periphery. Irritation of these roots, from 
whatever cause, excites convulsive movements in the muscles to which 
they are distributed; disease or division of these roots induces a condition 
of paresis or paralysis. 

The Function of the Posterior Roots is to transmit the impressions 
made upon the periphery to the centres in the spinal cord, where they 
excite motor impulses, or to the brain, in which they are translated into 
conscious sensations. Irritation of these roots gives rise to painful sensa¬ 
tions ; division of the roots abolishes all sensation in the parts to which 
they are distributed. 

The ganglion on the posterior root influences the nutrition of the sen- 
sory nerve; for if the nerve be separated from the ganglion, it undergoes 
degeneration in the course of a few days, in the direction in which it 
carries impressions, i. e., from the periphery to the centres; if the nerve be 


SPINAL NERVES. 


83 


divided between the ganglion and the cord, the central end only undergoes 
degeneration. The nutrition of the anterior root is governed by nerve 
cells in the gray matter of the cord; for if these cells undergo atrophy , or 
if the nerve be divided , it undergoes degeneration outward. 

Nerve Terminations, (i) Central. Both motor and sensory nerve 
fibres, as they enter the spinal cord and brain, lose their external invest¬ 
ments, and retaining only the axis cylinder, ultimately become connected 
with the processes of the gray cells. 

(2) Peripheral. As the nerves approach the tissues to which they are 
to be distributed, they inosculate freely, forming a plexus from which the 
ultimate fibres proceed to individual tissues. 

Motor Nerves. In the voluntary or striped muscles the motor nerves 
are connected with the contractile substance by means of the “ motorial 
end plates /” when the nerve enters the muscular fibre the tubular mem¬ 
brane blends with the sarcolemma, the medullary layer disappears, and 
the axis cylinder spreads out into the form of a little plate, granular in 
character, and containing oval nuclei. 

In the unstriped or involuntary muscles, the terminal nerve fibres form 
a plexus on the muscular fibre cells, and become connected with the 
granular contents of the nuclei. 

In the glands nerve fibres have been traced to the glandular cells, where 
they form a branching plexus from which fibres pass into their interior and 
become connected with their substance, and thus influence secretion. 

Sensitive Nerves terminate in the skin and mucous membranes, in 
three distinct modes, e.g., as tactile corpuscles, Pacinian corpuscles, and 
as end bulbs. 

The tactile corpuscles are found in the papillae of the true skin, espe¬ 
cially on the palmar surface of the hands and fingers, feet and toes; they 
are oblong bodies, measuring about of an inch in length, consisting 
of a central bulb of homogeneous connective tissue surrounded by elastic 
fibres and elongated nuclei. The nerve fibre approaches the base of the 
corpuscle, makes two or three spiral turns around it, and terminates in 
loops. They are connected with the sense of touch. 

The Pacinian corpuscles are found chiefly in the subcutaneous cellular 
tissue, on the nerves of the hands and feet, the intercostal nerves, the 
cutaneous nerves, and in many other situations. They are oval in shape, 
measure about the ^ of an inch in length on the average, and consist of 
concentric layers of connective tissue; the nerve fibre penetrates the cor¬ 
puscle and terminates in a rounded knob in the central bulb. Their 
function is unknown. 


84 


HUMAN PHYSIOLOGY. 


The end bulbs of Krause are formed of a capsule of connective tissue in 
which the nerve fibre terminates in a coiled mass or bulbous extremity; 
they exist in the conjunctiva, tongue, glans penis, clitoris, etc. 

Many sensitive nerves terminate in the papillae at the base of the hair 
follicle; but in the skin, mucous membranes, and organs of special sense 
their mode of termination is not well understood. 

f -1 

PROPERTIES AND FUNCTIONS OF NERVES. 

Classification. Nerves may be divided into two groups, viz.:— 

(1) Afferent or centripetal , as when they convey to the nerve centres the 
impressions which are made upon their peripheral extremities or parts of 
their course. They may be sensitive, when they transmit impressions which 
give rise to sensations; reflective or excitant, when the impression carried 
to the nerve centre is reflected outward by an efferent nerve and produces 
motion or some other effect in the part to which the nerve is distributed. 

(2) Efferent or centrifugal, as when the impulses generated in the 
centres are transmitted outward to the muscles and various organs. They 
may be motor, as when they convey impulses to the voluntary and invol¬ 
untary muscles; vaso-motor, when they regulate the calibre of the small 
blood vessels, increasing or diminishing the amount of blood to a part; 
secretory, when they influence secretion; trophic, when they influence 
nutrition; inhibitory, when they conduct impulses which produce a re¬ 
straining or inhibiting action. 

The Axis Cylinder is the essential conducting agent, the white substance 
of Schwann and tubular membrane being probably accessory structures, 
protecting the axis from injury, and preventing the diffusion of nerve force 
to adjoining nerves. 

The properties of sensation and motion reside in different nerve fibres. 
Motor nerves can be destroyed or paralyzed by the introduction of woorara 
under the skin, without affecting sensation; the sensibility of nerves can be 
abolished by the employment of anaesthetics without destroying motion. 

Irritability . Nerves conduct peripheral impressions to the centres, and 
motor impulses to the periphery, in virtue of their possessing an ultimate 
and inherent property, denominated neurility, nervous irritability, or 
excitability, which is manifested as long as the physical and chemical integ¬ 
rity of the nerve is maintained. 

Nerve degeneration . When nerves are separated from their trophic or 
nutritive centres, they degenerate progressively in the direction in which 
they conduct impressions. In motor nerves, from the centre to the pe¬ 
riphery ; in sensory nerves, from the periphery to the centres. 


PROPERTIES AND FUNCTIONS OF NERVES. 


85 


Nerve force is not identical with electricity. Nerves do not possess the 
power of generating force, or of originating impulses within themselves, 
but propagate only the nervous impulses which are called forth by chemi¬ 
cal, physical and mechanical stimuli from without, and by volitional acts, 
normal and pathological conditions from within. 

Phenomena of Muscles and Nerves. The muscles are the motor 
organs of the body and constitute a large per cent, of the body weight. 
Muscles are of two kinds, striated and non-striated or involuntary. The 
striated muscles consist of bundles of fibres, the fasciculi , held together 
by connective tissue. Each muscle fibre is about l / z to inches long, 
and possesses a delicate homogeneous membrane, the sarcolemma, in the 
interior of which is contained the contractile substance, which presents a 
striated appearance. During life this substance is in a fluid condition, but 
after death undergoes stiffening. 

The non-striated muscles form membranes which surround cavities, e. g., 
stomach, arteries, bladder, etc. They are composed of elongated cells 
without striations and contain in their interior one or more nuclei. 

Muscular tissue is composed of water, an organic contractile substance, 
myosin, non-nitrogenized substances, such as glycogen, inosite, fat, and 
inorganic salts. When at rest the muscle is alkaline in reaction, but 
during and after contraction it becomes acid. 

Muscles possess the properties of (i) Contractility, which is the capa¬ 
bility of shortening themselves in the direction of their long axis, and at 
the same time becoming thicker and more rigid. (2) Extensibility, by 
means of which they are lengthened in proportion to weights attached. 
(3) Elasticity, in virtue of which they return to their original shape when 
the force applied is removed. 

The contractility of muscles is called forth mainly by nervous impulses, 
descending motor nerves, which originate in the central nervous system ; 
but it can also be excited by the electric current, the application of strong 
acids, heat, or by mechanical means. 

Phenomena of a Muscular Contraction. When a single induc¬ 
tion shock is propagated through a nerve, the muscle to which it is dis¬ 
tributed undergoes a quick pulsation, and speedily returns to its former 
condition. As is shown by the muscle curve, the contraction, which is at first 
slow, increases in rapidity to its maximum, gradually relaxes and is again 
at rest, the entire pulsation not occupying more than the tV of a second. 

The muscular contraction does not instantly follow the induction shock, 
even when the electrodes are placed directly upon the muscular fibres 
themselves; an appreciable period intervenes before the contraction, 


86 


HUMAN PHYSIOLOGY. 


during which certain chemical changes are taking place preparatory to the 
manifestation of force. This is the “ latent period,” which has an average 
duration of the of a second, but varies with the temperature, the strength 
of the stimulus, the animal, etc. The muscular movements of "the body, 
however, are occasioned by contractions of a much longer duration, 
depending upon the number (the average, 20) of nervous impulses passing 
to the muscles in a second. 

During the muscular contraction the following phenomena are observed, 
viz : a change in form, a rise in temperature, a consumption of oxygen and 
an evolution of carbonic acid; the production of a distinct musical sound, 
a change from an alkaline to an acid reaction, from the development of 
sarcolactic acid; a disappearance of the natural muscle currents, which 
undergo a negative variation in the “ latent period,” just after the nervous 
impulse reaches the termination of the nerve, and before the appearance of 
the muscular contraction wave. 

Electrical Properties of Nerves. When a galvanic current is made 
to flow along a motor nerve from the centre to the periphery, from 
the positive to the negative pole, it is known as the direct , descending or 
centrifugal current. When it is made to flow in the reverse direction it is 
known as the inverse , ascending or centripetal current. 

The passage of a direct current enfeebles the excitability of a nerve; the 
passage of the inverse current increases it. The excitability of a nerve 
may be exhausted by the repeated applications of electricity ; when thus 
exhausted it may be restored by repose, or by the passage of the inverse 
current if the nerve has been exhausted by the direct current or vice versa. 

During the actual passage of a feeble constant current in either direction 
neither pain nor muscular contraction is ordinarily manifested; if the 
current be very intense the nerve may be disorganized and its excitability 
destroyed. 

Electrotonus. The passage of a direct galvanic current through a por¬ 
tion of a nerve excites in the parts beyond the electrodes a condition of 
electric tension or electrotonus , during which the excitability of the nerve 
is decreased near the anode or positive pole, and increased near the kathode 
or negative pole; the increase of excitability in the kathelectrotonic area , 
that nearest the muscle, being manifested by a more marked contraction 
of the muscle than the normal, when the nerve is irritated in this region. 
The passage of an inverse galvanic current excites the same condition 
of electrotonus; and the diminution of excitability near the anode, the 
anelectrotonic area , that now nearest the muscle, being manifested by a 
less marked contraction than the normal when the nerve is stimulated in 


CRANIAL NERVES. 


87 


this region. Between the electrodes is a neutral point where the kath- 
electrotonic area emerges into the anelectrotonic area. If the current be 
a strong one, the neutral point approaches the kathode; if weak, it ap¬ 
proaches the anode. 

When a nervous impulse passes along a nerve, the only appreciable 
effect is a change in its electrical condition, there being no change in its 
temperature, chemical composition or physical condition. The natural 
nerve currents, which are always present in a living nerve as a result 
of its nutritive activity, in great part disappear during the passage of an 
impulse, undergoing a negative variation. 

The rapidity with which nervous impulses are propagated along a nerve 
has been estimated at about ioo feet in a second for both motor and 
sensory nerves, but varies according to the temperature, the degree of 
excitability, the strength of the stimulus, etc. 

Law of Contraction. If a feeble galvanic current be applied to a 
recent and excitable nerve, contraction is produced in the muscles only 
upon the making of the circuit with both the direct and inverse current. 

If the current be moderate in intensity, the contraction is produced in 
the muscle both upon the making and breaking of the circuit, with both 
the direct and inverse currents. 

If the current be intense , contraction is produced only when the circuit 
is made with the direct current, and only when it is broken with the 
inverse current. 


CRANIAL NERVES. 


The Cranial Nerves come off from the base of the brain, pass through 
the foramina in the walls of the cranium, and are distributed to the skin, 
muscles and organs of sense in the face and head. 

According to the classification of Soemmering, there are 12 pairs of 
nerves, enumerating them from before backward, as follows, viz.:— 


1st Pair, or Olfactory. 

2d Pair, or Optic. 

3d Pair, or Motor oculi communis. 
4th Pair, or Patheticus, Trochlearis. 
5th Pair, or Trifacial, Trigeminus. 
6th Pair, or Abducens. 


7th Pair, or Facial, Portio dura. 

8th Pair, or Auditory, Portio mollis. 
9th Pair, or Glosso-pharyngeal. 
loth Pair, or Pneumogastric. 
nth Pair, or .Spinal accessory. 

12th Pair, or Hypoglossal. 


The Cranial Nerves may also be classified physiologically, according 
to their function, into three groups : 1. Nerves of special sense. 2. Nerves 
of motion. 3. Nerves of general sensibility. 


88 


HUMAN PHYSIOLOGY. 


i st Pair. Olfactory. 

Apparent Origin. From the inferior and internal portion of the an¬ 
terior lobes of the cerebrum by three roots, viz.: an external white rooty 
which passes across the fissure of Sylvius to the middle lobe of the cere¬ 
brum ; an internal white root, from the most posterior part of the anterior 
lobe; a. gray root , from the gray matter in the posterior and inner portion 
of the inferior surface of the anterior lobe. 

Deep Origin. Not satisfactorily determined. 

Distribution. The olfactory nerve, formed by the union of the three 
roots, passes forward along the under surface of the anterior lobe to the 
ethmoid bone, where it expands into the olfactory bulb. This bulb con¬ 
tains ganglionic cells, is grayish in color and soft in consistence; it gives 
off from its under surface from 15 to 20 nerve filaments, the true olfactory 
nerves, which pass through the cribriform plate of the ethmoid bone, and 
are distributed to the Schneiderian mucous membrane. This membrane 
extends from the cribriform plate of the ethmoid bone downward, about 
one inch. 

Properties. The olfactory nerves give rise to neither motor nor sensory 
phenomena when stimulated. They carry simply the special impressions of 
odorous substances. Destruction or injury of the olfactory bulbs is attended 
by a loss of the sense of smell. 

Function. Governs the sense of smell. Conducts the impressions 
which give rise to odorous sensations. 

2d Pair. Optic. 

Apparent Origin. From the anterior portion of the optic commissure. 

Deep Origin. An external xvhite root, from the corpus geniculatum 
externum; an internal white root, from the corpus geniculatum internum 
and the anterior tubercula quadrigemina; a gray root, from the gray matter 
in the floor of the 3d ventricle. Filaments also come from the optic thal- 
ami and cerebral peduncles. 4 

Distribution. The two roots unite to form a flattened band, the optic 
tract, which winds around the crus cerebri to decussate with the nerve of 
the opposite side, forming the optic chiasm. The decussation of fibres is 
not complete; some of the fibres of the left optic tract going to the outer 
half of the eye of the same side, and to the inner half of the eye of the 
opposite side; the same holds true for the right optic tract. 

The optic nerves proper arise, from the commissure, pass forward through 
the optic foramina, and are finally distributed in the retina. 


CRANIAL NERVES. 89 

Properties. They are insensible to ordinary impressions, and convey 
only the special impressions of light. 

Division of one of the nerves is attended by complete blindness in the 
eye of the corresponding side; division of the optic tract produces loss of 
sight in the outer half of the eye of the same side, and in the inner half 
of the eye of the opposite side. Lesion of the anterior part of the optic 
chiasm causes blindness in the inner half of the two eyes. 

Functions. Governs the sense of sight. Receives and conveys to the 
brain the luminous impressions which give rise to the sensation of sight. 

The reflex movements of the iris are called forth by the optic nerve. 
When an excess of light falls upon the retina the impression is carried 
back to the tubercula quadrigemina, where it is transformed into a motor 
impulse, which then passes outward through the motor oculi nerve to the 
contractile fibres of the iris and diminishes the size of the pupil. The 
absence of light is followed by a dilatation of the pupil. 

3d Pair. Motor Oculi Communis. 

Apparent Origin. From the inner surface of the crura cerebri. 

Deep Origin. By filaments coming from the lenticular nucleus, corpora 
quadrigemina, optic thalamus; these filaments converge to form a main 
trunk, which winds around the crus cerebri, in front of the pons Varolii. 

Distribution. The nerve then passes forward, and enters the orbit 
through the sphenoidal fissure, where it divides into a superior branch 
distributed to the superior rectus and levator palpebrce muscles; an inferior 
branch sending branches to the internal and inferior recti , and the inferior 
oblique muscles; filaments also pass into the ciliary or ophthalmic ganglion; 
from this ganglion the ciliary nerves arise which enter the eyeball, and are 
distributed to the circular fibres of the iris and the ciliary muscle. The 
3d nerve also receives filaments from the cavernous plexus of the sympa¬ 
thetic and from the 5th nerve. 

’'V ■ 

Properties. Irritation of the root of the nerve produces contraction 
of the pupil, internal strabismus, muscular movements of eye, but no pain. 
Division of the nerve is followed by ptosis (falling of the upper eyelid), 
external strabismus , due to the unopposed action of the external rectus 
muscle; dilatation of the pupil and persistent accommodation of the eye 
for long distances, from paralysis of the circular fibres of the iris and ciliary 
muscle; and inability to rotate the eye, slight protrusion and double vision, 
the images being on the same plane. 

Function. Governs movements of the eyeball by animating all the 
muscles except the external rectus and superior oblique, the movements of 
G 


90 


HUMAN PHYSIOLOGY. 


the iris, elevates the upper lid, influences the accommodation of the eye 
for distances. Can be called into action by (i) voluntary stimuli, (2) by 
reflex action through irritation of the optic nerve. 

4th Pair. Patheticus. 

Apparent Origin. From the superior peduncles of the cerebellum. 

Deep Origin. By fibres terminating in the corpora quadrigemina, len¬ 
ticular nucleus, valve of Vieussens, and in the substance of the cerebellar 
peduncles; some filaments pass over the median line and decussate with 
fibres of the opposite side. 

Distribution. The nerve enters the orbital cavity through the sphe¬ 
noidal fissure, and is distributed to the superior oblique muscle ; in its 
course receives filaments from the ophthalmic branch of the 5th pair and the 
sympathetic. 

Properties. When the nerve is irritated muscular movements are pro¬ 
duced in the superior oblique muscle, and the pupil of the eye is turned 
d ownward and outward. Division or paralysis of the nerve renders the eye- 
fa all immovable as far as rotation is concerned, and produces double vision. 

Function. Governs the movements of the eyeball produced by the 
action of the superior oblique muscles. 

6th Pair.* Abducens. Motor Oculi Externus. 

Apparent Origin. From the groove between the anterior pyramidal 
body and the pons Varolii, where it arises by two roots. 

Deep Origin. From the gray matter of the medulla oblongata. 

Distribution. The nerve then passes into the orbit through the sphe¬ 
noidal fissure, and is distributed to the external rectus muscle. Receives 
filaments from the cervical portion of the sympathetic, through the carotid 
plexus and spheno-palatine ganglion. 

Properties. When irritated , the external rectus muscle is thrown into 
convulsive movements, and the eyeball is turned outward. When divided 
or paralyzed, this muscle is paralyzed, and internal strabismus is produced. 

Function. To turn the eyeball outward. 

5th Pair. Trifacial. Trigeminal. 

Apparent Origin. By two roots from the side of the pons Varolii. 

Deep Origin. The deep origin of the two roots is the upper part of 
the floor and anterior wall of the 4th ventricle, by three bundles of fila- 

* The 6th nerve is considered in connection with the 3d and 4th nerves, since they 
together constitute the motor apparatus by which the ocular muscles are excited to action. 


CRANIAL NERVES. 


91 


ments, one of which anastomoses with the auditory nerve; another passes 
to the lateral tract of the medulla; while a third, grayish in color, goes to 
the restiform bodies, and may be traced to the point of the calamus 
scriptorius. 

Filaments of origin have been traced to the “ trigeminal sensory nucleus,” 
located on a level with the point of exit of the nerve, and to the posterior 
gray horns of the cord, as low down as the middle of the neck. 

Distribution. The large root of the nerve passes obliquely upward 
and forward to the ganglion of Gasser, which receives filaments of com¬ 
munication from the carotid plexus of the sympathetic. It then divides 
into three branches. 

1. Ophthalmic branch , which receives communicating filaments from 
the sympathetic, and sends sensitive fibres to all the motor nerves of the 
eyeball. It is distributed to the ciliary ganglion, lachrymal gland, sac and 
caruncle, conjunctiva, integument of the upper eyelid, forehead, side of 
head and nose, anterior portion of the scalp, ciliary muscle and iris. 

2. Superior maxillary branch , sends branches to the spheno-palatine 
ganglion, integument of the temple and lower eyelid, side of forehead, 
nose, cheek and upper lip, teeth of the upper jaw, and alveolar processes. 

3. Inferior maxillary branch , which, after receiving in its course fila¬ 
ments from the small root and from the facial, is distributed to the sub¬ 
maxillary ganglion, the parotid and sub-lingual glands, external auditory 
meatus, mucous membrane of the mouth, anterior two-thirds of the tongue 
(lingual branch), gums, arches of the palate, teeth of the lower jaw, and 
integument of the lower part of the face, and to the muscles of mastication. 

The small root passes forward beneath the ganglion of Gasser, through 
the foramen ovale, and joins the inferior maxillary division of the large 
root, which then divides into an anterior and posterior branch, the former 
of which is distributed to the muscles of mastication, viz: temporal, 
masseter, internal and external pterygoid muscles. 

Properties. It is the most acutely sensitive nerve in the body, and 
endows all the parts to which it is distributed with general sensibility. 

Irritation of the large root , or any of its branches, will give rise to 
marked evidence of pain; the various forms of neuralgia of the head and 
face being occasioned by compression, disease, or exposure of some of its 
terminal branches. 

Division of the large root within the cranium is followed at once by a 
complete abolition of all sensibility in the head and face, but is not attended 
by any loss of motion. The integument, mucous membranes and the eye 
may be lacerated, cut or bruised, without the animal exhibiting any 


92 


HUMAN PHYSIOLOGY. 


evidence of pain. At the same time the lachrymal secretion is diminished, 
the pupil becomes contracted, the eyeball is protruded, and the sensibility 
of the tongue is abolished. 

The reflex movements of deglutition are also somewhat impaired; the 
impression of the food being unable to reach and excite the nerve centre 
in the medulla oblongata. 

Galvanization of the small root produces movements of the muscles of 
mastication ; section of the root causes paralysis of these muscles, and the 
jaw is drawn to the opposite side, by the action of the opposing muscles. 

Influence upon the Special Senses. After division of the large 
root within the cranium, a disturbance in the nutrition of the special senses 
sooner or later manifests itself. 

Sight. In the course of 24 hours the eye becomes very vascular and 
inflamed, the cornea becomes opaque and ulcerates, the humors are dis¬ 
charged, and the eye is totally destroyed. 

Smell. The nasal mucous membrane swells up, becomes fungous, and 
is liable to bleed on the slightest irritation. The mucus is increased in 
amount, so as to obstruct the nasal passages; the sense of smell is finally 
abolished. 

Hearing. At times the hearing is impaired, from disorders of nutrition 
in the middle ear and external auditory meatus. 

Alteration in the nutrition of the special senses is not marked if the sec¬ 
tion is made posterior to the ganglion of Gasser, and to the anastomosing 
filaments of the sympathetic which join the nerve at this point; but if the 
ganglion be divided, these effects . are very noticeable, due to the section 
of the sympathetic filaments. 

Function. Gives sensibility to all parts of the head and face to which 
it is distributed; through the small root endows the masticatory muscles 
with motion; through fibres from the sympathetic governs the nutrition of 
the special senses. 

7th Pair. Portio Dura. Facial Nerve. 

Apparent Origin. From the groove between the olivary and restiform 
bodies at the lateral portion of the medulla oblongata, and below the 
margin of the pons Varolii. 

Deep Origin. From a nucleus of large cells in the floor of the 4th 
ventricle, below the nucleus of origin of the 6th pair, with which it is 
connected. Some filaments are traceable to the lenticular nucleus of the 
opposite side. Some of the fibres cross the median line and decussate. It 
is intimately associated with the nerve of Wrisberg at its origin. 


CRANIAL NERVES. 


93 


Distribution. From its origin the facial nerve passes into the internal 
auditory meatus, and then, in company with the nerve of Wrisberg, enters 
the aqueduct of Fallopius. The filaments of the nerve of Wrisberg are 
supplied with a ganglion, of a reddish color, having nerve cells. These 
filaments unite with those of the root of the facial, to form a common 
trunk, which emerges at the stylo-mastoid foramen. 

In the aqueduct the facial gives off the following branches, viz.:— 

1. Large petrosal nerve , which passes forward to the spheno-palatine, or 
Meckel’s ganglion, and through this to the levator palati and azygos uvulae 
muscles, which receive motor influence from this source. 

2. Small petrosal ne 7 ~ve, passing to the otic ganglion and thence to the 
tensor-tympani muscle, endowing it with motion. 

3. Tympanic branch , giving motion to the stapedius muscle. 

4. Chorda tympani nerve, which after entering the posterior part of the 
tympanic cavity, passes forward between the malleus and incus bones, 
through the Glasserian fissure, and joins the lingual branch of the 5th 
nerve. It is then distributed to the mucous membrane of the anterior 
two-thirds of the tongue and the sub-maxillary glands. 

After emerging from the stylo mastoid foramen, the facial nerve sends 
branches to the muscles of the ear, the occipito-frontalis, the digastric, 
the palato-glossi, and palato-pharyngei; after which it passes through 
the parotid gland and divides into the temporo-facial and cervico-facial 
branches, which are distributed to the superficial muscles of the face, viz.: 
occipito-frontalis, corrugator supercilii, orbicularis palpebrarum, levator 
labii superioris et alseque nasi, buccinator, levator anguli oris, orbicularis 
oris, zygomatici, depressor anguli oris, platysma myoides, etc. 

Properties. Undoubtedly a motor nerve at its origin, but in its course 
receives sensitive filaments from the 5th pair and the pneumogastric. 

Irritation of the nerve, after its emergence from the stylo-mastoid fora¬ 
men, produces convulsive movements in all the superficial muscles of the 
face. Division of the nerve at this point causes paralysis of these muscles 
on the side of the section, constituting facial paralysis; the phenomena of 
which are, a relaxed and immobile condition of the same side of the face; 
the eyelids remain open, from paralysis of the orbicularis palpebrarum ; 
the act of winking is abolished; the angle of the mouth droops, and saliva 
constantly drains away; the face is drawn over to the sound side; the face 
becomes distorted upon talking or laughing; mastication is interfered with, 
the food accumulating between the gums and cheek, from paralysis of the 
buccinator muscle; fluids escape from the mouth in drinking; articulation 
is impaired, the labial sounds being imperfectly pronounced. 


94 


HUMAN PHYSIOLOGY. 


Properties of the branches given off in the aqueduct of Fallopius. The 
Largepetrosal y when irritated, throws the levator palati and azygos uvulas 
muscles into contraction. Paralysis of this nerve, from deep-seated lesions, 
produces a deviation of the uvula to the sound side, a drooping of the 
palate, and an inability to elevate it. 

The Small petrosal influences hearing by animating the tensor tympani 
muscle; when paralyzed, there occurs partial deafness and an increased 
sensibility to sonorous impressions. 

The Tympanic branch animates the stapedius muscle, and influences 
audition. 

The Chorda tympani influences the circulation and the secretion of 
saliva, in the sub-maxillary glands, and governs the sense of taste in the 
anterior two-thirds of the tongue. Galvanization of the chorda tympani 
dilates the blood vessels, increases the quantity and rapidity of the stream 
of blood, and increases the secretion of saliva. Division of the nerve is 
followed by contraction of the vessels, an arrestation of the secretion, and 
a diminution of the sense of taste, on the same side. 

Function. The facial is the nerve of expression, and co-ordinates the 
muscles employed to delineate the various emotions, influences the sense 
of taste, deglutition, movements of the uvula and soft palate, the tension of 
the membrana tympani, and the secretions of the sub-maxillary and parotid 
glands. Indirectly influences smell, hearing and vision. 

8th Pair. Portio Mollis. Auditory Nerve. 

Apparent Origin. From the upper and lateral portion of the medulla 
oblongata, just below the margin of the pons Varolii. 

Deep Origin. By two roots from the floor of the 4th ventricle, each 
root consisting of a number of gray filaments, some of which decussate in 
the median line • the external root has a gangliform enlargement contain¬ 
ing fusiform nerve cells. 

Distribution. The two roots wind around the restiform bodies and 
enter the internal auditory meatus, and divide into an anterior branch 
distributed to the cochlea, and a posterior branch distributed to the vesti¬ 
bule and semicircular canals. 

Properties. They are soft in consistence, grayish in color, consisting 
of axis cylinders with a medullary sheath only; they are not sensible to 
ordinary impressions, but convey the impression of sound. 

Function. Governs the sense of hearing. Receives and conducts to the 
brain the impression of sound, which give rise to the sensations of hearing. 


CRANIAL NERVES. 


95 


gth Pair. Glosso-pharyngeal. 

Apparent Origin. Partly from the medulla oblongata and the inferior 
peduncles of the cerebellum. 

Deep Origin. From the lower portion of the gray substance in the 
floor of the 4th ventricle. 

This nerve has two ganglia; the jugular ganglion includes only a por¬ 
tion of the root filaments; the ganglion of Andersch includes all the fibres 
of the trunk. 

Distribution. The trunk of the nerve passes downward and forward, 
receiving near the ganglion of Andersch fibres from the facial and pneu- 
mogastric nerves. It divides into two large branches, one of which is 
distributed to the base of the tongue, the other to the pharynx. In its 
course it sends filaments to the otic ganglion; a tympanic branch which 
gives sensibility to the mucous membrane of the fenestra rotunda, fenestra 
ovalis, and Eustachian tube; lingual branches to the base of the tongue; 
palatal branches to the soft palate, uvula and tonsils; pharyngeal branches 
to the mucous membrane of the pharynx. 

Properties. Irritation of the roots at their origin calls forth evidences 
of pain; it is, therefore, a sensory nerve, but its sensibility is not so acute 
as that of the tri-facial. Irritation of the trunk after its exit from the 
cranium produces contraction of the muscles of the palate and pharynx, 
due to the presence of anastomosing motor fibres. 

Division of the nerve abolishes sensibility in the structures to which it 
is distributed, and impairs the sense of taste in the posterior third of the 
tongue (see Sense of Taste). 

Function. Governs sensibility of pharynx, presides partly over the sense 
of taste, and controls reflex movements of deglutition and vomiting. 

10th Pair. Pneumogastric. Par Vagum. 

Apparent Origin. From the lateral side of the medulla oblongata, 
just behind the olivary body. 

Deep Origin. In the gray nuclei in the lower half of the floor of the 
4th ventricle, and in the substance of the restiform body. Some filaments 
are traced along the restiform tract, toward the cerebellum, and others to 
the median line of the floor of the 4th ventricle, where many of them 
decussate. 

This nerve has two ganglia; one in the jugular foramen, called the gan¬ 
glion of the root, and another outside of the cranial cavity on the trunk, 
the ganglion of the trunk. 


96 


HUMAN PHYSIOLOGY. 


Distribution. The filaments from the root unite to form a single trunk, 
which leaves the cavity of the cranium, through the jugular foramen, in 
company with the spinal accessory and glosso-pharyngeal. It soon receives 
an anastomotic branch from the spinal accessory , and afterward branches 
from the facial, the hypoglossal and the anterior branches of the two upper 
cervical nerves. 

As the nerve passes down the neck it sends off the following main 
branches:— 

1. Pharyngeal nerves, which assist in forming the pharyngeal plexus, 
which is distributed to the mucous membrane and muscles of the pharynx. 

2. Superior laryngeal nerve, which enters the larynx through the thyro¬ 
hyoid membrane, and is distributed to the mucous membrane lining the 
interior of the larynx, and to the crico-thyroid muscle and the inferior 
constrictor of the pharynx. The “ depressor nerve,” found in the rabbit, 
is formed by the union of two branches, one from the superior laryngeal, 
the other from the main trunk; it passes downward to be distributed to 
the heart. 

3. Inferior laryngeal, which sends its ultimate branches to all the in¬ 
trinsic muscles of the larynx except the crico-thyroid, and to the inferior 
constrictor of the pharynx. 

4. Cardiac branches given off from the nerve throughout its course 
which unite with the sympathetic fibres to form the cardiac plexus, to be 
distributed to the heart. 

5. Pulmonary branches, which form a plexus of nerves and are dis¬ 
tributed to the bronchi and their ultimate terminations, the lobules and air 
cells. 

From the right pneumogastric nerve branches are distributed to the mucous 
membrane and muscular coats of the stomach and intestines, to the liver, 
spleen, kidneys, and supra-renal capsules. 

Properties. At its origin the pneumogastric nerve is sensory, as shown 
by direct irritation or galvanization, though its sensibility is not very 
marked. In its course exhibits motor properties, from anastomosis with 
motor nerves. 

The Pharyngeal branches assist in giving sensibility to the mucous mem¬ 
brane of the pharynx, and influence reflex phenomena of deglutition 
through motor fibres which they contain, derived from the spinal accessory. 

The Superior laryngeal nerve endows the upper portion of the larynx 
with sensibility; protects it from the entrance of foreign bodies; by con¬ 
ducting impressions to the medulla, excites the reflex movements of deglu- 


CRANIAL NERVES. 


97 


tition and respiration; through. the motor filaments it contains produces 
contraction of the crico-thyroid muscle. 

Division of the “ Depressor nerve” and galvanization of the central 
end, retards and even arrests the pulsations of the heart, and by depressing 
the vaso-motor centre diminishes the pressure of blood in the large vessels, 
by causing dilatation of the intestinal vessels through the splanchnic 
nerves. 

The Inferior laryngeal contains, for the most part, motor fibres from 
the spinal accessory. When irritated , produces movement in the laryn¬ 
geal muscles. When divided, is followed by paralysis of these muscles, 
except the crico-thyroid, impairment of phonation, and an embarrassment 
of the respiratory movements of the larynx, and finally death, from suffo¬ 
cation. 

The Cardiac branches, through filaments derived from the spinal acces¬ 
sory, exert a direct inhibitory action upon the heait. Division of the 
pneumogastrics in the neck increases the frequency of the heart’s action. 
Galvanization of the peripheral ends diminishes the heart’s pulsation, and, 
if sufficiently powerful, paralyzes it in disatole. 

The Pulmonary branches give sensibility to the bronchial mucous mem¬ 
brane, and govern the movements of respiration. Division of both pneu¬ 
mogastrics in the neck diminishes the frequency of the respiratory move¬ 
ments, falling as low as 4 to 6 per minute; death usually occurs in from 5 
to 8 days. Feeble galvanization of the central ends of the divided nerves 
accelerates respiration; powerful galvanization retards, and may even 
arrest, the respiratory movements. 

The Gastric branches give sensibility to the mucous coat, and through 
sympathetic filaments, which join the pneumogastrics high up in the neck, 
give motion to the muscular coat of the stomach. They influence the 
secretion of gastric juice, aid the process of digestion and absorption from 
the stomach. 

The Hepatic branches, probably through anastomosing sympathetic fila¬ 
ments, influence the secretion of bile, and the glycogenic function of the 
liver; division of the pneumogastrics in the neck produces congestion of 
the liver, diminishes the density of the bile, and arrests the glycogenic 
function; galvanization of the central ends exaggerates the glycogenic 
function, and makes the animal diabetic. 

The Intestinal branches give sensibility and motion to the small in¬ 
testines, and when divided, purgatives generally fail to produce purgation. 

Function. A great sensitive nerve which, through anastomotic fila¬ 
ments from motor sources, influences deglutition, the action of the heart, 


98 


HUMAN PHYSIOLOGY. 


the circulatory and respiratory systems, voice, the secretions of the stomach, 
intestines, and various glandular organs. 

nth Pair. Spinal Accessory. 

Apparent Origin. By two sets of filaments :— 

1. A bulbar or medullary set, four or five in number, from the lateral 
or motor tract of the lower half of the medulla oblongata, below the origin 
of the pneumogastric. 

2. A spinal set, from 6 to 8 in number, from the lateral portion of the 
spinal cord, between the anterior and posterior roots of the upper four or 
five cervical nerves. 

Deep Origin. The medullary portion arises in a nucleus in the lower 
half of the floor of the 4th ventricle, common to the pneumogastric and 
glosso pharyngeal nerves. The spinal portion has its origin in an elon¬ 
gated nucleus lying along the external surface of the anterior cornua of 
the spinal cord, extending down to the 5th cervical vertebra. 

Distribution. From this origin the fibres unite to form a main trunk, 
which enters the cranial cavity through the foramen magnum, where it is 
at times joined by fibres from the posterior roots of the two upper cervical 
nerves, and sends filaments to the ganglion of the root of the pneumo¬ 
gastric. After emerging from the cranial cavity through the jugular fora¬ 
men, it sends a branch to the pneumogastric, and receives others in return, 
and also from the 2d, 3d and 4th cervical nerves. It divides into two 
branches: (1) An internal or anastomotic branch, made up of filaments 
coming principally from the medulla oblongata, and is distributed to the 
muscles of the pharynx through the pharyngeal nerves coming from the 
pneumogastric; to all the muscles of the larynx, except the crico-thyroid 
through the inferior laryngeal nerve; to the heart, by filaments which 
reach it through the pneumogastric nerve. (2) An external branch, which 
is distributed to the sterno-cleido-mastoid and trapezius muscles; these 
muscles also receiving filaments from the cervical nerves. 

Properties. At its origin it is a purely motor nerve, but in its course 
exhibits some sensibility from anastomosing fibres. 

Destruction of the medullary root , by tearing it from its attachment by 
means of forceps, impairs the action of the muscles of deglutition, and 
destroys the power of producing vocal sounds by paralysis of the laryngeal 
muscles, without, however, interfering with the respiratory movements of 
the larynx ; these being controlled by other motor nerves. The normal 
rate of movement of the heart is also 'impaired by destruction of the 
medullary root. 


CRANIAL NERVES. 


99 


Irritation of the external branch throws the trapezius and sterno-mastoid 
muscles into convulsive movements, though section of the nerve does not 
produce complete paralysis, as they are also supplied with motor influence 
from the cervical nerves. The sterno-mastoid and trapezius muscles per¬ 
form movements antagonistic to those of respiration, fixing the head, neck 
and upper part of the thorax, and delaying the expiratory movement during 
the acts of pushing, pulling, straining, etc., and in the production of a pro¬ 
longed vocal sound, as in singing. When the external branch alone is 
divided, in animals, they experience shortness of breath during exercise, 
from a want of coordination of the muscles of the limbs and respiration; 
and while they can make a vocal sound, it cannot be prolonged. 

Function. Governs phonation by its influence upon the vocal move¬ 
ments of the glottis ; influences the movements of deglutition, inhibits the 
action of the heart and controls certain respiratory movements associated 
with sustained or prolonged muscular efforts and phonation. 

12th Pair. Hypoglossal or Sublingual. 

Apparent Origin. By two groups of filaments from the medulla ob¬ 
longata, in the grooves between the olivary body and the anterior pyramid. 

Deep Origin. From the hypoglossal nucleus situated deeply in the 
substance of the medulla, on a level with the lowest portion of the floor 
of the 4th ventricle; some decussating filaments have been traced to a 
higher encephalic centre. 

Distribution. The trunk formed by the union of the root filaments 
passes out of the cranial cavity through the anterior condyloid foramen, 
occasionally receiving a filament from the lateral and posterior portion of 
the medulla oblongata. After emerging from the cranium, it sends filaments 
to the sympathetic and pneumogastric; it anastomoses with the lingual 
branch of the 5th pair, and receives and sends filaments to the upper cer¬ 
vical nerves. The nerve is finally distributed to the sterno-hyoid, sterno¬ 
thyroid, omo-hyoid, thyro-hyoid, stylo glossi, hyo-glossi, genio-hyoid 
genio-hyo-glossi, and the intrinsic muscles of the tongue. 

Properties. A purely motor nerve at its origin, but derives sensibility 
outside of the cranial cavity, from anastomosis with the cervical, pneumo¬ 
gastric and 5th nerves. 

Irritation of the nerve gives rise to convulsive movements of the tongue 
and slight evidences of sensibility. 

Division of the nerve abolishes all movements of the tongue, and inter¬ 
feres considerably with the act of deglutition. 


100 


HUMAN PHYSIOLOGY. 


When the hypoglossal nerve is involved in hemiplegia, the tip of the 
tongue is directed to the paralyzed side when the tongue is protruded; 
due to the unopposed action of the genio-hyo-glossus on the sound side. 

Articulation is considerably impaired in paralysis of this nerve; great 
difficulty being experienced in the pronunciation of the consonantal sounds. 

Mastication is performed with difficulty, from inability to retain the food 
between the teeth until it is completely triturated. 

Function. Governs all the movements of the tongue and influences the 
functions of mastication, deglutition and articulate language. 


CEREBRO-SPINAL AXIS. 

The Cerebro-Spinal Axis consists of the spinal cord, medulla oblon¬ 
gata, pons Varolii, cerebellum and cerebrum, exclusive of the spinal and 
cranial nerves. It is contained within the cavities of the cranium and 
spinal column, and surrounded by three membranes, the dura mater, 
arachnoid and pia mater, which protect it from injury and supply it with 
blood vessels. 

The Brain and Spinal Cord are composed of both white fibres and 
collections of gray cells, and are, therefore, to be regarded as conductors 
of impressions and motor impulses, as well as generators of nerve force. 

MEMBRANES. 

The Dura Mater, the most external of the three, is a tough membrane, 
composed of white fibrous tissue, arranged in bundles, which interlace in 
every direction. In the cranial cavity it lines the inner surface of the 
bones, and is attached to the edge of the foramen magnum; sends 
processes inward, forming the falx cerebri, falx cerebelli, and tentorium 
cerebelli, supporting and protecting parts of the brain. In the spinal canal 
it loosely invests the cord, and is separated from the walls of the canal by 
areolar tissue. 

The Arachnoid, the middle membrane, is a delicate serous structure 
which envelopes the brain and cord, forming the visceral layer , and is 
then reflected to the inner surface of the dura mater, forming the parietal 
layer. Between the two layers there is a small quantity of fluid which 
prevents friction by lubricating the two surfaces. 

The Pia Mater, the most internal of the three, composed of areolar 
tissue and blood vessels, covers the entire surface of the brain and cord, to 
which it is closely adherent, dipping down between the convolutions and 


SPINAL CORD. 101 

fissures. It is exceedingly vascular, sending small blood vessels some dis¬ 
tance into the brain and cord. 

The Cerebro-Spinal Fluid occupies the sub-arachnoid space, and the 
general ventricular cavities of the brain, which communicate by an opening, 
the foramen of Magendie, in the pia mater, at the lower portion of the 4th 
ventricle. This fluid is clear, transparent,’ alkaline, possesses a salt taste 
and a low specific gravity; it is composed largely of water, traces of albu¬ 
men, glucose and mineral salts. It is secreted by the pia mater; the 
quantity is estimated from 2 to 4 fluid oz. 

The function of the cerebro-spinal fluid is to protect the brain and cord, 
by preventing concussion from without; by being easily displaced into the 
spinal canal, prevents undue pressure and insufficiency of blood to the 
brain. 

SPINAL CORD. 

The Spinal Cord varies from 16 to 18 inches in length; is half an inch 
in thickness, weighs 1 oz., and extends from the atlas to the 2d lumbar 
vertebra, terminating in the filum terminate. It is cylindrical in shape, 
and presents an enlargement in the lower cervical and lower dorsal 
regions, corresponding to the origin of the nerves which are distributed to 
the upper and lower extremities. The cord is divided into two lateral 
halves by the anterior and posterior fissures. It is composed of both ivhite 
or fibrous and gray or vesicular matter, the former occupying the exterior 
of the cord, the latter the interior, where it is arranged in the form of two 
crescents, one in each lateral half, united together by the central mass, the 
gray commissure; the white matter being united in front by the white 
commissure. 

Structure of the White Matter. The white matter surrounding each 
lateral half of the cord is made up of nerve fibres, some of which are 
continuations of the nerves which enter the cord, while others are derived 
from different sources. It is subdivided into: (1) An Anterior column, 
comprising that portion between the anterior roots and the anterior fissure, 
which is again subdivided into two parts: ( a ) an inner portion, bordering 
the anterior median fissure, the direct pyramidal tract, or column of Tiirck, 
containing motor fibres which do not decussate, and which extends as far 
down as the middle of the dorsal region; ( b ) an outer portion, surrounding 
the anterior cornua, known as the anterior root zone, composed of short 
longitudinal fibres which serve to connect together different segments of 
the spinal cord. (2) A Lateral column, the portion between the anterior 
and posterior roots, which is divisible into [a] the crossed pyramidal tract , 


102 


HUMAN PHYSIOLOGY. 


occupying the posterior portion of the lateral column, and containing all 
those fibres of the motor tract which have decussated at the medulla ob¬ 
longata; it is composed of longitudinally running fibres which are con¬ 
nected with the multipolar nerve cells of the anterior cornua; (b) the 
direct cerebellar tract , situated upon the surface of the lateral column, 
consisting of longitudinal fibres which terminate in the cerebellum ; it first 
appears in the lumbar region, and increases as it passes upward; (c) the 
anterior tract, lying just posterior to the anterior cornua. (3) A Posterior 
column, the portion included between the posterior roots and the posterior 
fissure, also divisible into two portions, ( a ) an inner portion, the postero¬ 
internal column , or the column of Goll, bordering the posterior median 
fissure, and {b) an external portion, the postero-external column , the 
column of Burdach, lying just behind the posterior roots. They are com¬ 
posed of long and short commissural fibres which connect together different 
segments of the spinal cord. 

Structure of the Gray Matter. The gray matter, arranged in the 
form of two crescents, presents an anterior and posterior horn. It is made 
up of a delicate network of fine nerve fibres (axis cylinders), supported by 
a connective tissue framework of nucleated nerve cells, which in the 
anterior horns are large and multipolar, and connected with the anterior 
roots of spinal nerves; in the posterior horns the nerve cells are smaller, 
and situated along the inner margin, and in the caput cornu. Small cells 
are also found in the posterior vesicular columns, and in the intermediary 
lateral tract. 

COURSE OF THE ANTERIOR AND POSTERIOR ROOTS. 

The Anterior Roots pass through the anterior columns, horizontally, 
in straight and distinct bundles, and enter the anterior cornuse, where they 
diverge in four directions. (1) Many become connected with the prolon¬ 
gations of the multipolar nerve cells. (2) Others leave the gray matter, 
pass through the anterior white commissure, and enter the anterior columns 
of the opposite side. (3) A considerable number enter the lateral columns 
of the same side, through which they pass to the medulla oblongata, where 
they decussate and finally terminate in the corpus striatum of the opposite 
side. (4) Others traverse the gray matter horizontally, and come into 
relation with the posterior roots. 

The Posterior Roots enter the posterior horns of the gray matter (1) 
through the substantia gelatinosa, (2) to the inner side; of the former , 
some bend upward and downward, and become connected with the ante¬ 
rior cornuae; others pass through the posterior commissure to the opposite 


SPINAL CORD. 


103 



Diagram showing the course, through the spinal cord, of the motor and sensory nerve 
fibres. B and B' represent the right and left hemispheres of the brain, from which the 
motor fibres take their origin, and in which the sensory fibres terminate. The motor 
tract from the right side 1 passes down through the crus, through the pons to the 
medulla oblongata, where it divides into two portions ; n st, the larger -portion, ninety- 
seven per cent., crosses over to the opposite side of the cord and passes down through 
the lateral column. It gives off fibres at different levels, which pass into the gray mat¬ 
ter and become connected with the muscles, M, through the multipolar cells; the smaller 
portion, three per cent., does not cross over, but descends on the same side of the cord in 
the anterior column and supplies the muscles, m. The same is true for the motor tract 
for the left hemisphere. 

The sensory fibres from the left side of the body enter the gray matter through 
the posterior roots. They then cross over at once to the opposite side of the cord and 
ascend to the hemisphere partly in the gray matter, partly in the posterior column. 
The same is true for the sensory nerves of the right side of the body. 



















































104 


HUMAN PHYSIOLOGY. 


side; of the latter , fibres pass into the gray matter, to the posterior vesicu¬ 
lar columns, passing obliquely through the posterior white columns upward 
and downward for some distance, and enter the gray matter at different 
heights. 

Decussation of Motor and Sensory Fibres. The Motor fibres, 
which conduct volitional impulses from the brain outward to the anterior 
cornuse, arise in the motor centres of the cerebrum; they then pass down¬ 
ward through the corona radiata, the internal capsule, the inferior portions 
of the crura cerebri, the pons Varolii, to the medulla oblongata, where the 
motor tract of each side divides into two portions, viz.: i. The larger , 
containing 91 to 97 per cent, of the fibres, which decussates at the lower 
border of the medulla and passes down in the lateral column of the oppo¬ 
site side, and constitutes the crossed pyramidal tract. 2. The smaller , 
containing 3 to 9 percent, of the fibres, does not decussate, but passes down 
the ante 7 'ior column of the same side, and constitutes the direct pyramidal 
tract , or the column of Tiirck. Some of the motor fibres of these two 
tracts, after entering the anterior cornuoe of the gray matter, become con¬ 
nected with the large multipolar nerve cells, while others pass directly into 
the anterior roots. Through this decussation each half of the brain governs 
the muscular movements of the opposite side of the body. 

The Sensory fibres, which convey the impression made upon the peri¬ 
phery to the cord and brain, pass into the cord through the posterior roots 
of spinal nerves ; they then diverge and enter the gray matter at different 
levels, and at once decussate, passing to the opposite side of the gray 
matter. The sensory tract passes upward, through the cord, the medulla, 
pons Varolii, the superior portion of the crura cerebri, the posterior third 
of the internal capsule, to the sensory perceptive centre, located in the 
hippocampus major and unciate convolution (Ferrier). Through this de¬ 
cussation each half of the brain governs the sensibility of the opposite half 
of the body. 

Properties of the Spinal Cord. Irritation applied directly to the 
antero-lateral white columns produces muscular movements but no pain ; 
they are, therefore, excitable but insensible. 

The surface of the posterior columns is very sensitive to direct irritation, 
especially near the origin of the posterior roots; less so toward the pos¬ 
terior median fissure. The sensibility is due, however, not to its own 
proper fibres, but to the fibres of the posterior roots which traverse it. 

Division of the antero-lateral columns abolishes all power of voluntary 
movement in the lower extremities. 


FUNCTIONS OF THE SPINAL CORD. 


105 


Division of the posterior columns impairs the power of muscular co¬ 
ordination, such as is witnessed in locomotor ataxia. 

The gray matter is probably both insensible and inexcitable under the 
influence of direct stimulation. 

A transverse section of one lateral half of the cord produces:— 

(1) On the same side, paralysis of voluntary motion and a relative or 
absolute elevation of temperature and an increased flow of blood in the 
paralyzed parts; hypersesthesia lor the sense of contact, tickling, pain and 
temperature. 

(2) On the opposite side, complete anaesthesia as regards contact, and 
tickling and temperature, in the parts corresponding to those which are 
paralyzed in the opposite side. Complete preservation of voluntary power 
and of the muscular sense. 

A vertical section through the middle of the gray matter results in the 
loss of sensation on both sides of the body below the section, but no loss 
of voluntary power. 

FUNCTIONS OF THE SPINAL CORD. 

1. As a Conductor. The Lateral columns , particularly the posterior 
portions, the “pyramidal tracts,” and the columns of Tiirck, are the 
channels through which pass the voluntary motor impulses from the brain 
to the large multipolar nerve cells in the anterior cornuse of gray matter, 
and through them become connected with the anterior roots which transmit 
the motor stimuli to the muscles. 

The Anterior columns , especially the portion surrounding the anterior 
cornuae, the “ anterior radicular zones,” are composed of short longitudinal 
commissural fibres, which serve to connect together different segments of 
the spinal cord, a condition required for the coordination of muscular 
movements. 

The Posterior columns are composed of short and long commissural 
fibres which connect together different segments of the cord. They are 
insensible to direct irritation, but aid in the coordination of muscular move¬ 
ments in walking, standing, running, etc. Degeneration of the posterior 
columns gives rise to the lack of muscular coordination observed in loco¬ 
motor ataxia. 

The Gray matter , and especially that portion immediately surrounding 
the central canal, transmits the sensory nerve fibres from the posterior 
roots up to the brain. Decussation of the sensory fibres takes place 
throughout the whole length of the gray matter. 

H 


106 


HUMAN PHYSIOLOGY. 


The Multipolar cells of the anterior cornuce are connected with the gen- 
eration and transmission of motor impulses outward ; are centres for reflex 
movements; are the trophic centres for the motor nerves and muscular 
fibres to which they are distributed. The anterior roots give passage to 
the vaso-constrictor and vaso-dilator fibres which exert an influence upon 
the calibre of the blood vessels. Complete destruction of the anterior 
horns is followed by a paralysis of motion, degeneration of the anterior 
roots, atrophy of muscles and bones and an abolition of reflex movements. 

2. As an Independent Nerve Centre. 

The spinal cord, by virtue of its containing ganglionic nerve matter, is 
capable of transforming impressions made upon the centripetal nerves into 
motor impulses, which are reflected outward through centrifugal nerves to 
muscles, producing movements. These reflex movements taking place 
through the gray matter, are independent of sensation and volition. 

The mechanism involved in every reflex act is a sentient surface, a 
sensory nerve, a nerve centre, a motor nerve and muscle. 

The rejlex excitability of the cord may be— 

(i) Increased by disease of the lateral columns, the administration of 
strychnia, and in frogs, by a separation of the cord from the brain, the 
latter apparently exerting an inhibitory influence over the former and de¬ 
pressing its reflex activity. 

2. Inhibited by destructive lesions of the cord, e. g., locomotor ataxia, 
atrophy of the anterior cornuae, the administration of various drugs, and, in 
the frog, by irritation of certain regions of the brain. When the cerebrum 
alone is removed and the optic lobes stimulated, the time elapsing between 
the application of an irritant to a sensory surface and the resulting move¬ 
ment will be considerably prolonged. The optic lobes (Setchenow’s centre) 
apparently generating impulses which, descending the cord, retard its 
reflex movements. 

All movements taking place through the nervous system are of this reflex 
character, and may be divided into excito-motor, sensori-motor and ideo¬ 
motor. 

Classification of Reflex Movements. (Kiiss.) They may be divided 
into four groups, according to the route through which the centripetal and 
centrifugal impulses pass. 

1. Those normal reflex acts, e. g., deglutition, coughing, sneezing, walk¬ 
ing, etc., pathological reflex acts, e.g., tetanus, vomiting, epilepsy, which 
take place both centripetally and centrifugally, through spinal nerves. 

2. Reflex acts which take place in a centripetal direction through a 


FUNCTIONS OF THE SPINAL CORD. 


107 


cerebro-spinal sensory nerve, and in a centrifugal direction through a sym¬ 
pathetic motor nerve, usually a vaso-motor nerve, e.g., the normal reflex 
acts, which give rise to most of the secretions, pallor and blushing of the 
skin, certain movements of the iris, certain modifications in the beat of the 
heart; the pathological, which, on account of the difficulty in explaining 
their production, are termed metastatic, e. g., ophthalmia, coryza, orchitis, 
which depend on a reflex hypersemia; amaurosis, paralysis, paraplegia, 
etc., due to a reflex anaemia. 

3. Reflex movements, in which the centripetal impulse passes through a 
sympathetic nerve, and the centrifugal through a cerebro-spinal nerve; 
most of these phenomena are pathological, e. g., convulsions from intestinal 
irritation produced by the presence of worms, eclampsia, hysteria, etc. 

4. Reflex actions, in which both the centripetal and centrifugal impulses 
pass through filaments of the sympathetic nervous system, e. g., those ob¬ 
scure reflex actions which preside over the secretions of the intestinal 
fluids, which unite the phenomena of the generative organs, the dilatation 
of the pupils from intestinal irritation (worms), and many pathological 
phenomena. 

Laws of Reflex Action. (Pfliiger.) 

1. Law of Unilaterality. If a feeble irritation be applied to one or 
more sensory nerves, movement takes place usually on one side only, and 
that upon the same side as the irritation. 

2. Law of Symmetry. If the irritation becomes sufficiently intense, 
motor reaction is manifested, in addition, in corresponding muscles of the 
opposite side of the body. 

3. Law of Intensity. Reflex movements are usually more intense on 
the side of the irritation ; at times the movements of the opposite side 
equal them in intensity, but they are usually less pronounced. 

4. Law of Radiation. If the excitation still continues to increase, it is 
propagated upward, and motor reaction takes place through centrifugal 
nerves coming from segments of the cord higher up. 

5. Law of Generalization. When the irritation becomes very intense, 
it is propagated to the medulla oblongata; motor reaction then becomes 
general, and is propagated up and down the cord, so that all the muscles 
of the body are thrown into action, the medulla oblongata acting as a focus 
whence radiate all reflex movements. 

Special Centres in the Spinal Cord. 

Genito-spinal centre. In the lower portion of the spinal cord are 
located the centres which control the sphincter muscles of the rectum and 


108 


HUMAN PHYSIOLOGY. 


bladder, the erection of the penis, the emission of the semen, the action of 
the uterus during parturition, etc. 

Cilio-spinal centre. Situated in the spinal cord between the 6th cervical 
and 2d dorsal nerves; stimulation of the cord in this situation produces a 
dilatation of both pupils through filaments of the sympathetic, which take 
their origin from this region of the cord. 

Throughout the spinal cord are situated numerous centres which preside 
over the following reflexes, viz:— 

The patellar tendon reflex takes place through the segments from which 
arise the 2d, 3d and 4th lumbar nerves; the cremasteric reflex through the 
segment from which arise the 1st and 2d lumbar nerves; the abdominal 
reflex through the segments between the 8th and 12th dorsal nerves; the 
epigastric reflex through the segments from which arise the 4th, 5th and 
6th dorsal nerves. 

Paralysis from Disease of the Spinal Cord. 

Seat of Lesion. If it be in the lower part of the sacral canal, there is 
paralysis of the compressor urethrae, accelerator urinae, and sphincter ani 
muscles; no paralysis of the muscles of the leg. 

At the upper limit of the sacral region. Paralysis of the muscles of 
the bladder, rectum and anus; loss of sensation and motion in the muscles 
of the legs, except those supplied by the anterior crural and obturator, 
viz: psoas iliacus, Sartorius, pectineus, adductor longus, magnus and 
brevis, obturator, vastus externus and internus, etc. 

At the upper limit of the lumbar region. Sensation and motion para¬ 
lyzed in both legs; loss of power over the rectum and bladder; paralysis 
of the muscular walls of the abdomen interfering with expiratory move¬ 
ments. 

At the lower portion of the cervical region. Paralysis of the legs, etc., 
as above; in addition, paralysis of all the intercostal muscles and conse- 
sequent interference with respiratory movements ; paralysis of muscles of 
the upper extremities, except those of the shoulders. 

Above the middle of the cervical region. In addition to the preceding, 
difficulty of deglutition and vocalization, contraction of the pupils, paralysis 
of the diaphragm, scalene muscles, intercostals, and many of the accessory 
respiratory muscles; death resulting immediately, from arrest of respiratory 
movements. 

Anterior half of spinal cord. Paraplegia developing symmetrically. 

Posterior half of spinal cord. Characteristic symptoms of locomotor 
ataxia or tabes dorsalis. 


MEDULLA OBLONGATA. 


109 


In the gray substance in the vicinity of the central canal and anterior^ 
horns. If the lesion be acute, symptoms characteristic of acute spinal 
paralysis manifest themselves; if chronic, symptoms characteristic of 
progressive muscular atrophy. 

MEDULLA OBLONGATA. 

The Medulla Oblongata is the expanded portion of the upper part of 
the spinal cord. It is pyramidal in form and measures one and a half 
inches in length, three-quarters of an inch in breadth, half an inch in 
thickness, and is divided into two lateral halves by the anterior and pos- 



View of Cerebellum in section, and of Fourth Ventricle, with the neighboring parts. 
{From Sappey.) 

i. Median groove fourth ventricle, ending below in the calamus scriptorius , with 
the longitudinal eminences formed by the fasciculi teretes, one on each side. 2. The same 
groove, at the place where the white streaks of the auditory nerve emerge from it to 
cross the floor of the ventricle. 3. Inferior peduncle of the cerebellum, formed by the 
restiform body. 4. Posterior pyramid, above this is the calamus scriptorius. 5. Supe¬ 
rior peduncle of cerebellum, or processus e cerebello ad testes. 6 6. Fillet to the side 
of the crura cerebri. 7 7. Lateral grooves of the crura cerebri. 8. Corpora quad- 
rigemina.—After Hirschfeld and Leveille. 

terior median fissures, which are continuous with those of the cord. Each 
half is again subdivided by minor grooves, into four columns, viz : anterior 
pyramid , lateral tract and olivary body , restiform body and posterior 
Pyramid. 


110 


HUMAN PHYSIOLOGY. 


1. The anterior pyramid is composed partly of fibres continuous with 
those of the anterior column of the spinal cord; but mainly of fibres derived 
from the lateral tract of the opposite side, by decussation. The united fibres 
then pass upward through the pons Varolii and crura cerebri, and for the 
most part terminate in the corpus striatum and cerebrum. 

2. The lateral tract is continuous with the lateral columns of the cord; 
its fibres in passing upward take three directions, viz-;* an external bundle 
joins the restiform body, and passes into the cerebellum; an internal bundle 
decussates at the median line and joins the opposite anterior pyramid; a 
middle bundle ascends beneath the olivary body, behind the pons, to the 
cerebrum, as the fasciculus teres. 

The olivary body of each side is an oval mass, situated between the 
anterior pyramid and restiform body; it is composed of white matter ex¬ 
ternally and gray matter internally, forming the corpus dentatum. 

3. The restiform body , continuous with the posterior column of the cord, 
also receives fibres from the lateral column. As the restiform bodies pass 
upward they diverge and form a space, the 4th ventricle, the floor of which 
is formed by gray matter, and then turn backward and enter the cerebellum. 

4. The posterior pyramid is a narrow, white cord bordering the posterior 
median fissure; it is continued upward, in connection with the fasciculus 
teres , to the cerebrum. 

The Gray Matter of the medulla is continuous with that of the cord. 
It is arranged with much less regularity, becoming blended with the white 
matter of the different columns, with the exception of the anterior. By 
the separation of the posterior columns, the transverse commissure is 
exposed, forming part of the floor of the 4th ventricle; special collections 
of gray matter are found in the posterior portions of the medulla, connected 
with the roots of origin of different cranial nerves. 

Properties and Functions. The medulla is excitable anteriorly, 
and sensitive posteriorly to direct irritation. It serves (1) as a conductor 
of sensitive impressions upward from the cord, through the gray matter to 
the cerebrum; (2) as a conductor of voluntary impulses from the brain to 
the spinal cord and nerves, through its anterior pyramids; (3) as a con¬ 
ductor of coordinating impulses from the cerebellum, through the restiform 
bodies to the spinal cord. 

As an Independent Reflex Centre. The medulla oblongata con¬ 
tains special collections of gray matter, which constitute independent 
nerve centres which preside over different functions, some of which are 
as follows, viz :— 


MEDULLA OBLONGATA. 


Ill 


!• A centre which controls the movements of mastication, through affer¬ 
ent and efferent nerves. (See page 24.) 

2. A centre reflecting impressions which influence the secretion of saliva. 
(See page 25.) 

3. A centre for deglutition, whence are derived motor stimuli exciting to 
action and coordinating the muscles of the palate, pharynx and oesophagus, 
necessary for the swallowing of the food. 


NERVOUS 

Excitor 

or 

Centripetal 

Nerves. 

Motor 

or 

Centrifugal 

Nerves. 


CIRCLE OF DEGLUTITION. (2d and 3 d Stages.) 
Palatal branch of 5th pair. 

Pharyngeal branches of the glosso-pharyngeal. 
Superior laryngeal branches of the pneumogastric. 
(Esophageal branches of the pneumogastric. 
Pharyngeal branches of the pneumogastric, derived 
from the spinal accessory. 

Hypoglossal and branches of the cervical plexus. 
Inferior or recurrent laryngeal. 

Motor filaments of the 3d division of the 5th pair. 
Portio dura. 


-I 


4. A centre which coordinates the muscles concerned in the act of 
vomiting. 

5. A Speech centre , coordinating the various muscles necessary for the 
accomplishment of articulation through the hypoglossal, facial nerves and 
the 2d divisioAof the 5th pair. 

6. A centre for the harmonization of muscles concerned in expression , 
reflecting its impulses through the facial nerve. 

7. A Cardiac centre , which exerts (1) an accelerating influence over the 
heart’s pulsations through accelerating nerve fibres emerging from the cer¬ 
vical portion of the cord, entering the inferior cervical ganglion, and thence 
passing to the heart; (2) an inhibitory or retarding influence upon the 
action of the heart, through fibres of the spinal accessory nerve running in 
the trunk of the pneumogastric. 

8. A Vaso motor centre , which, by alternately contracting and dilating the 
blood vessels through nerves distributed in their walls, regulates the quantity- 
of blood distributed to an organ or tissue, and thus influences nutrition, secre¬ 
tion and calorification. The vaso-motor centre is situated in the medulla 
oblongata and pons Varolii, between the corpora quadrigemina and the 
calamus scriptorius. The vaso-motor fibres having their origin in this 
centre descend through the interior of the cord, emerge through the anterior 
roots of spinal nerves, enter the ganglia of the sympathetic, and thence 





112 


HUMAN PHYSIOLOGY. 


pass to the walls of the blood vessels, and maintain the arterial tonus ; 
they may be divided into two classes, viz: vaso-dilators, e. g., chorda 
tympani, and vaso-constrictors, e.g., sympathetic fibres. 

Division of the cord at the lower border of the medulla is followed by 
a dilatation of the entire vascular system and a marked fall of the blood 
pressure. Galvanic stimulation of the divided surface of the cord is fol¬ 
lowed by a contraction of the blood vessels and a rise in the blood pressure. 

9. A Diabetic centre, irritation of which causes an increase in the 
amount of urine secreted, and the appearance of a considerable quantity 
of sugar. 

10. A Respiratory centre , situated near the origin of the pneumogastric 
nerves, presides over the movements of respiration and its modifications, 
laughing, sighing, sobbing, sneezing, etc. It may be excited rejlexly by 
the presence of carbonic acid in the lungs irritating the terminal pneumo¬ 
gastric filaments; or automatically , according to the character of the blood 
circulating through it; an excess of carbonic acid or a diminution of oxygen 
increasing the number of respiratory movements; a reverse condition di¬ 
minishing the respiratory movements. 

11. A Spasm centre , stimulation of which gives rise to convulsive phe¬ 
nomena. 

NERVOUS CIRCLE OF RESPIRATION (ENTIRELY REFLEX). 

Pulmonary branches of the pneumogastric. 

Superior laryngeal. 

Trifacial, or 5th pair. 

Nerves of general sensibility. 

Sympathetic nerve. 

Phrenic, distributed to the diaphragm. 

Intercostals, distributed to the intercostal muscles. 
Facial nerve, or portio dura, to the facial muscles. 
External branch of spinal accessory, to the trapezius 
„ and sterno-cleido-mastoid muscles. 


Excitor 

or 

Centripetal 

Nerves. 

Motor 

or 

Centrifugal 

Nerves. 


PONS VAROLII. 

The Pons Varolii unites together the cerebrum above, the cerebellum 
behind, and the medulla oblongata below. It consists of transverse and 
longitudinal fibres, amidst which are irregularly scattered collections of 
gray or vesicular nervous matter. 

The transverse fibres unite the two lateral halves of the cerebellum. 




CRURA CEREBRI. 


113 


The longitudinal fibres are continuous (i) with the anterior pyramids of 
the medulla oblongata, which interlacing with the deep layers of the 
transverse fibres, ascend to the crura cerebri, forming their superficial or 
fasciculated portions; (2) with fibres derived from the olivary fasciculus, 
some of which pass to the tubercula quadrigemina, while others, uniting 
with fibres from the lateral and posterior columns of the medulla, ascend 
in the deep or posterior portions of the crura cerebri. 

Properties and Functions, The superficial portion is insensible and 
inexcitable to direct irritation; the deeper portions appear to be excitable , 
consisting of descending motor fibres; the posterior portions are sensible 
but inexcitable to irritation. 

Transmits motor impulses and sensory impressions from and to the 
cerebrum. 

The gray ganglionic matter consists of centres which convert impres¬ 
sions into conscious sensations, and originate motor impulses, these taking 
place independent of any intellectual process; they are the seat of instinct¬ 
ive reflex acts; the centres which assist in the co-ordination of the auto¬ 
matic movements of station and progression. 


CRURA CEREBRI. 

The Crura Cerebri are largely composed of the longitudinal fibres of 
the pons (anterior pyramids, fasciculi teretes); after emerging from the 
pons they increase in size, and become separated into two portions by a 
layer of dark gray matter, the locus niger. 

The superficial portion, the crusta, composed of the anterior pyramids, 
constitutes the motor tract , which terminates, for the most part, in the 
corpus striatum , but to some extent, also, in the cerebrum; the deep por¬ 
tion , made up of the fasciculi teretes and posterior pyramids and accessory 
fibres from the cerebellum, constitute the sensory tract (the tegmentum ), 
whieh terminates in the optic thalamus and cerebrum. 

Function. The crura are conductors of motor impulses and sensory 
impressions; the gray matter, the locus niger , assists in the coordination of 
the complicated movements of the eyeball and iris, through the motor oculi 
communis nerve. They also assist in the harmonization of general muscu¬ 
lar movements; section of one crus giving rise to peculiar movements of 
rotation and somersaults forward and backward. 


114 


HUMAN PHYSIOLOGY. 


CORPORA QUADRIGEMINA. 

The Corpora Quadrigemina are four small, rounded eminences, two 
en each side of the median line, situated immediately behind the third 
ventricle, and beneath the posterior border of the corpus callosum. 

The anterior tubercles are oblong from before backward, and larger 
than the posterior , which are hemispherical in shape ; they are grayish in 
color, but consist of white matter externally and gray matter internally. 

Both the anterior and posterior tubercles are connected with the optic 
thalami by commissural bands named the anterior and posterior brachia , 
respectively. They receive fibres from the olivary fasciculus and fibres from 
the cerebellum, which pass upward to enter the optic thalami. 

The corpora geniculata are situated, one on the inner side and one on 
the outer side of each optic tract, behind and beneath the optic thalamus, 
and from their position are named the corpora geniculata interna and 
externa; they give origin to fibres of the optic nerve. 

Functions. The Tubercula quadrigemina are the physical centres of 
sight, translating the luminous impressions into visual sensations. Destruc¬ 
tion of these tubercles is immediately followed bv a loss of the sense of 
sight; moreover, their action in vision is crossed, owing to the decussation 
of the optic tracts, so that if the tubercle of the right side be destroyed by 
disease or extirpated, in a pigeon, the sight is lost in the eye of the oppo¬ 
site side, and the iris loses its mobility. 

The tubercula quadrigemina as nerve centres preside over the reflex 
movements which cause a dilation or contraction of the iris; irritation of 
the tubercles causing contraction, destruction causing dilatation. Removal 
of the tubercles on one side produces a temporary loss of power of the 
opposite side of the body, and a tendency to move around an axis is 
manifested, as after a section of one crus cerebri, which, however, may be 
due to giddiness and loss of sight. 

They also assist in the coordination of the complex movements of the 
eye, and regulate the movements of the iris during the movements of 
accommodation for distance. 

CORPORA STRIATA AND OPTIC THALAMI. 

The Corpora Striata are two large ovoid collections of gray matter, 
situated at the base of the cerebrum, the larger portions of which are 
imbedded in the white matter, the smaller portions projecting into the 
anterior part of the lateral ventricle. Each striated body is divided, by a 
narrow band of white matter, into two portions, viz : — 


CORPORA STRIATA AND OPTIC THALAMI. 


115 . 


1. The Caudate nucleus , the intraventricular portion, which is conical 
in shape, having its apex directed backward, as a narrow, tail-like process. 

2. The Lenticular nucleus , imbedded in the white matter, and for the 
most part external to the ventricle; on the outer side of the lenticular 
nucleus is found a narrow band of white matter, the external capsule; 
and between it and the convolutions of the island of Reil, a thin band of 
gray matter, the claustrum ; the corpora striata are grayish in color, and 
when divided present transverse striations, from the intermingling of white 
fibre and gray cells. 

The Optic Thalami are two oblong masses situated in the ventricles 
posterior to the corpora striata, and resting upon the posterior portion of 
the crura cerebri. The internal surface projecting into the lateral ven¬ 
tricles is white, but the interior is grayish, from a commingling of both 
white fibres and gray cells. Separating the lenticular nucleus from the 
caudate nucleus and the optic thalamus, is a band of white tissue, the 
internal capsule. 

The internal capsule is a narrow, bent tract of white matter, and is, for 
the most part, an expansion of the motor tract of the crura cerebri. It 
consists of two segments, an anterior , situated between the caudate 
nucleus and the anterior surface of the lenticular nucleus, and & posterior, 
situated between the optic thalamus and the posterior surface of the len¬ 
ticular nucleus. These two segments unite at an obtuse angle, which is 
directed towards the median line. Pathological observation has shown 
that the nerve fibres of the direct and crossed pyramidal tracts can be 
traced upward through the anterior two-thirds of the posterior segment, 
into the centrum ovale, where, for the most part, they are lost; a portion, 
however, remaining united, ascend higher and terminate in the paracentral 
lobule, the superior extremity of the ascending frontal and parietal convo¬ 
lutions. The sensory tract can be traced upward, through the posterior 
third, into the cerebrum, where they probably terminate in the hippo¬ 
campus major and unciate convolution. 

Functions. The Corpora striata are the centres in which terminate 
some of the fibres of the superficial or motor tract of the crura cerebri; 
others pass upward through the internal capsule , to be distributed to the 
cerebrum. It might be inferred, from their anatomical relations, that they 
are motor centres. Irritation by a weak galvanic current produces mus¬ 
cular movements of the opposite side of the body; destruction of their 
substance by a hemorrhage, as in apoplexy, is followed by a paralysis of 
motion of the opposite side of the body, but there is no loss of sensation. 


116 


HUMAN PHYSIOLOGY. 


When the hemorrhagic destruction involves the fibres of the anterior two- 
thirds of the posterior segment of the internal capsule, and thus separates 
them from their trophic centres in the cortical motor region, a descending 
degeneration is established, which involves the direct pyramidal tract of 
the same side and the crossed pyramidal tract of the opposite side. 

Destruction of the posterior one-third of the posterior segment of the 
internal capsule is followed by a loss of sensation on the opposite side of 
the body, and a loss of the senses of smell and vision on the same side 
(Charcot). The precise function of the corpora striata is unknown, but 
they are in some way connected with motion. 

The Optic thalami receive the fibres of the tegmentum , the posterior 
portion of the crura cerebri. They are insensible and inexcitable to direct 
irritation. Removal of one optic thalamus, or destruction of its substance 
by disease or hemorrhage, is followed by a loss of sensibility of the oppo¬ 
site side of the body, but there is no loss of motion; their precise function 
is also unknown, but in some way connected with sensation. In both cases 
their action is crossed. 

CEREBELLUM. 

The Cerebellum is situated in the inferior fossae of the occipital bone, 
beneath the posterior lobes of the cerebrum. It attains its maximum 
weight, which is about 5 oz., between the twenty-fifth and fortieth years; 
the proportion between the cerebellum and cerebrum being 1 to 8^. 

It is composed of two lateral hemispheres and a central elongated lobe, 
the vermiform process; the two hemispheres are connected with each 
other by the fibres of the middle peduncle forming the superficial portion 
of the pons Varolii. It is brought into connection with the medulla 
oblongata and spinal cord , through the prolongation of the restiform bodies; 
with the cerebrum, by fibres passing upward beneath the corpora quadri- 
gemina and the optic thalami, and then forming part of the diverging cere¬ 
bral fibres. 

Structure. It is composed of both white and gray matter, the former 
being internal, the latter external, and convoluted, for economy of space. 

The White 7 ?iatter consists of a central stem, the interior of which is 
a dentated capsule of gray matter, the corpus dentatum. From the external 
surface of the stem of white matter processes are given off, forming the 
lamince , which are covered with gray matter. 

The Gray matter is convoluted and covers externally the laminated pro¬ 
cesses ; a vertical section through the gray matter reveals the following 
structures:— 


' CEREBELLUM. 


117 


1. A delicate connective tissue layer , just beneath the pia mater, contain¬ 
ing rounded corpuscles, and branching fibres passing toward the external 
surface. 

2. The cells of Purkinje , forming a layer of large, nucleated, branched 
nerve cells sending off processes to the external layer. 

3. A granular layer of small, but numerous corpuscles. 

4. Nerve fibre layer , formed by a portion of the white matter. 

Properties and Functions. Irritation of the cerebellum is not fol¬ 
lowed by any evidences either of pain or convulsive movements; it is, 
therefore, insensible and inexcitable. 

Co-ordination of Movements. Removal of the superficial portions 
of the cerebellum in pigeons produces feebleness and want of harmony 
in the muscular movements; as successive slices are removed, the move¬ 
ments become more irregular, and the pigeon becomes restless; when 
the last portions are removed, all power of flying, walking, standing, etc., 
is entirely gone, and the equilibrium cannot be maintained, the power of 
coordinating muscular movements being entirely gone. The same results 
have been obtained by operating on all classes of animals. 

The following symptoms were noticed by Wagner, after removing the 
whole or a large part of the cerebellum. 1. A tendency on the part of 
the animal to throw itself on one side, and to extend the legs as far as 
possible. 2. Torsion of the head on the neck. 3. Trembling of the 
muscles of the body, which was general. 4. Vomiting and occasionally 
liquid evacuations. 

Forced Movements. Division of one crura cerebelli causes the animal 
to fall on one side and roll rapidly on its longitudinal axis. According to 
Schiff, if the peduncle be divided from behind , the animal falls on the 
same side as the injury; if the section be made in front, the animal turns 
to the opposite side. 

Disease of the cerebellum partially corroborates the results of experi¬ 
ments; in many cases symptoms of unsteadiness of gait, from a want of 
coordination, have been noticed. 

Comparative anatomy reveals a remarkable correspondence between 
the development of the cerebellum and the complexity of muscular actions. 
It attains a much greater development, relatively to the rest of the brain, 
in those animals whose movements are very complex and varied in char¬ 
acter, such as the kangaroo, shark and swallow. 

The cerebellum may possibly exert some influence over the sexual func¬ 
tion, but physiological and pathological facts are opposed to the idea of 


118 


HUMAN PHYSIOLOGY. 


its being the seat of the sexual instinct. It appears to be simply a centre 
for the coordination and equilibration of muscular movements. 

CEREBRUM. 

The Cerebrum is the largest portion of the encephalic mass, constitut¬ 
ing about four-fifths of its weight; the average weight in the adult male 
is from 48 to 50 oz., or about 3 pounds, white in the adult female it is 
about 5 oz. less. After the age of 40 the weight of the cerebrum gradually 
diminishes at the rate of one ounce every ten years. In idiots the brain 
weight is often below the normal, at times not amounting to more than 20 
ounces. 

The Blood Supply to the cerebrum is unusually large, considering its 
comparative bulk; nearly one-fifth, of the entire volume of blood being 
distributed to it by the carotid and vertebral arteries. These vessels anas¬ 
tomose so freely, and are so arranged within the cavity of the cranium, that 
an obstruction in one vessel will not interfere with the regular supply of 
blood to the parts to which its branches are distributed. A diminished 
amount, or complete cessation, of the supply of blood is at once followed 
by a suspension of its functional activity. 

The cerebrum is connected with the pons Varolii and medulla oblon¬ 
gata through the crura cerebri, and with the cerebellum, through the supe¬ 
rior peduncles. It is divided into two lateral halves, or hemispheres, by 
the longitudinal fissure running from before backward in the median line ; 
each hemisphere is composed of both white and gray matter, the former 
being internal, the latter external; it covers the surfaces of the hemisphere 
which are infolded, forming convolutions, for economy of space. 

Fissures. 

1. The Fissure of Sylvius is one of the most important; it is the first to 
appear in the development of the foetal brain, being visible at about the 
third month; in the adult it is quite deep and well marked, running from 
the under surface of the brain upward, outward and backward, and forms 
a boundary between the frontal and temporo-sphenoidal lobes. 

2. The Fissure of Rolando is second in importance, and runs from 
a point on the convexity near the median line transversely outward and 
downward toward the fissure of Sylvius, but does not enter it. It sepa¬ 
rates the frontal from the parietal lobe. 

3. The Parietalfissure , arising a short distance behind the fissure of Ro¬ 
lando, upon the convexity of the hemisphere, runs downward and back¬ 
ward to its posterior extremity. 


CEREBRUM. 


119 


Secondary fissures of importance are found in different lobes of the 
cerebrum, separating the various convolutions. In the anterior lobe are 
found the pre-central , superiorfrontal and inferior frontal fissures; in the 
occipital lobe, are found the parieto-occipital and the calcarine fissures. 

Convolutions. Frontal Lobe. 

The Ascending frontal convolution , situated in front of the fissure of 
Rolando, runs downward and forward; it is continuous above with the 
anterior frontal, and below with the inferior frontal convolution. 

The Superior frontal convolution is bounded internally by the longitu¬ 
dinal fissure, and externally by the superior frontal fissure; it is connected 
with the superior end of the frontal convolution, and runs downward and 
forward to the anterior extremity of the frontal lobe, where it turns back¬ 
ward, and rests upon the orbital plate of the frontal bone. 

The Middle frontal convolution , the largest of the three, runs from be¬ 
hind forward, along the sides of the lobe, to its anterior part; it is bounded 
above by the superior and below by the inferior frontal fissures. 

The Inferior frontal convolution winds around the ascending branch 
of the fissure of Sylvius, in the anterior and inferior portion of the 
cerebrum. 

Parietal Lobe. The Ascending parietal convolution is situated just be¬ 
hind the fissure of Rolando, running downward and forward; above, it 
becomes continuous with the upper parietal convolution, and below, winds 
around to be united with the ascending frontal. 

The Upper parietal convolution is situated between the parietal and 
longitudinal fissures. 

The Supra-marginal convolution winds around the superior extremity 
of the fissure of Sylvius. 

The Angular convolution , a continuation of the preceding, follows the 
parietal fissure to its posterior extremity, and then makes a sharp angle 
downward and forward. 

Temporo-sphenoidal Lobe. Contains three well marked convolutions, 
the superior , middle and inferior , separated by well defined fissures, and 
continuous posteriorly with the convolutions of the parietal lobe. 

The Occipital Lobe lies behind the parieto-occipital fissure, and contains 
the superior , middle and inferior convolutions, not well marked. 

The Central Lobe or Island of Reil, situated at the bifurcation of the 
fissure of Sylvius, is a triangular-shaped cluster of six convolutions, the gyri 
operti, which are connected with those of the frontal, parietal, and tem¬ 
poro-sphenoidal lobes. 


120 


HUMAN PHYSIOLOGY. 


Structure. The Gray matter of the cerebrum, about one-eighth of an 
inch thick, is composed of five layers of nerve cells: (i) a superficial 
layer, containing few small multipolar ganglion cells; (2) small ganglion- 
cells, pyramidal in shape; (3) a layer of large pyramidal ganglion cells 
with processes running off superiorly and laterally; (4) the granular forma¬ 
tion containing nerve cells; (5) spindle shaped and branching nerve cells 
of moderate size. 

The White Matter consists of three distinct sets of fibres— 

1. The diverging or peduncular fibres are mainly derived from the 
columns of the cord and medulla oblongata; passing upward through the 
crura cerebri, they receive accessory fibres from the olivary fasciculus, cor¬ 
pora quadrigemina and cerebellum. Some of the fibres terminate in the 
optic thalami and corpora striata, while others radiate into the anterior, 
middle and posterior lobes of the cerebrum. 

2. The transverse commissural fibres connect together the two hemi¬ 
spheres, through the corpus callosum and anterior and posterior commis¬ 
sures. 

3. The longitudinal commissural fibres connect together different parts 
of the same hemisphere. 

Functions. The cerebral hemispheres are the centres of the nervous 
system through which are manifested all the phenomena of the mind; 
they are the centres in which impressions are registered, and reproduced 
subsequently as ideas ; they are the seat of intelligence, reason and will. 

However important a centre the cerebrum may be, for the exhibition of 
this highest form of nervous action, it is not directly essential for the con¬ 
tinuance of life; for it does not exert any control over those automatic 
reflex acts, such as respiration, circulation, etc., which regulate the func¬ 
tions of organic life. 

From the study of comparative anatomy, pathology, vivisection, etc., 
evidence has been obtained which throws some light upon the physiology 
of the cerebral hemispheres. 

1. Comparative Anatomy shows that there is a general connection be¬ 
tween the size of the brain, its texture, the depth and number of convolu¬ 
tions, and the exhibition of mental power. Throughout the entire animal 
series, the increase in intelligence goes hand in hand with an increase in 
the development of the brain. In man there is an enormous increase in 
size over that of the highest animals, the anthropoids. The most cultivated 
races of men have the greatest cranial capacity; that of the educated 
European being about 116 cubic inches, that of the Australian being about 


CEREBRUM. 


121 


60 cubic inches, a difference of 56 cubic inches. Men distinguished for 
great mental power usually have large and well developed brains; that of 
Cuvier weighed 64 oz.; that of Abercrombie 63 oz.; the average being 
about 48 to 50 oz.; not only the size, but above all, the texture of the 
brain, must be taken into consideration. 

2. Pathology. Any severe injury or disease disorganizing the hemi¬ 
spheres is at once attended by a disturbance, or entire suspension of mental 
activity. A blow on the head producing concussion, or undue pressure 
from cerebral hemorrhage destroys consciousness; physical and chemical 
alterations in the gray matter have been shown to coexist with insanity, 
loss of memory, speech, etc. Congenital defects of organization from im¬ 
perfect develop ment are usually accompanied by a corresponding deficiency 
of intellectual power and the higher instincts. Under these circumstances 
no great advance in mental development can be possible, and the intelli¬ 
gence remains at a low grade. In congenital idiocy not only is the brain 
of small size, but it is wanting in proper chemical composition; phosphorus , 
a characteristic ingredient of the nervous tissue, being largely diminished 
in amount. 

3. Experimentation upon the lower animals by removing the cerebral 
hemispheres is attended by results similar to those observed in disease and 
injury. Removal of the cerebrum in pigeons produces complete abolition 
of intelligence, and destroys the capability of performing spontaneous 
movements. The pigeon remains in a condition of profound stupor, which 
is not accompanied, however, by a loss of sensation, or of the power of pro¬ 
ducing reflex or instinctive movements. The pigeon can be temporarily 
aroused by pinching the feet, loud noises, light placed before the eyes, etc., 
but soon relapses into a state of quietude, being unable to remember im¬ 
pressions and connect them with any train of ideas; the faculties of 
memory, reason and judgment being completely abolished. 

LOCALIZATION OF FUNCTIONS. 

The Faculty of articulate language , by which the individual associates 
ideas and words comprises two distinct faculties, viz: 1. The power of 

recalling particular words; 2. The coordination of muscles necessary for 
their articulation. 

Aphasia is a condition in which the power of expressing ideas in words 
is completely lost. Pathological observation has shown that this condition 
is frequently associated with disease of the 3dfrontal convolution of the 
left side, and also the convolutions of the island of Reil, parts nourished by 
the middle cerebral artery. It usually coexists with right hemiplegia; at 


I 


122 


HUMAN PHYSIOLOGY. 


times aphasia results from disease of corresponding structures of the 
right side. The faculty of articulate language may be located in the 
3d frontal convolution and the island of Reil, usually on the left side of 
the brain. 

Motor Centres. The gray matter covering the cerebral hemispheres 
is both insensible and inexcitable to ordinary mechanical and chemical 
stimuli; but when a galvanic current of low intensity is applied to par¬ 
ticular regions of the cerebrum of a monkey, in which the general 
arrangement of the convolutions approximates that of man, definite co¬ 
ordinate movements occur on the opposite side of the body, e. g., rotation, 
flexion and extension of the limbs, and movements of the facial muscles. 

The regions in which the motor centres are located are the convolutions 
around the fissure of Rolando, especially the ascending frontal and the 
ascending parietal. Destruction of the gray matter of these convolutions 
is followed by a paralysis of motion on the opposite side of the body; 
destruction of circumscribed areas in these convolutions causes paralysis 
of the groups of muscles excited to action by electrical stimulation of such 
areas. 

The antero-frontal and occipital lobes are not excitable to electrical 
stimulation. 

Special Centres. The superior and middle frontal convolutions 
appear to be connected with the intellectual faculties; ablation of these 
convolutions causes a marked impairment of the intelligence and of the 
faculty of attentive observation, without impairing either sensation or 
motion. 

The Visual centre is located in the angular convolution. If this centre 
be destroyed, blindness of the opposite eye results, which is, however, only 
temporary if the opposite angular convolution be intact; destruction of 
both causes a complete and permanent loss of visual perceptions. 

The Auditory and Taste centres are located in the superior and inferior 
temporo sphenoidal convolutions respectively; destruction of these regions 
abolishes the sense of hearing and taste. The sense of smell is situated in 
the uncinate convolution or cornu ammonis. 

Systemic sensations are probably located in the occipital lobes; their 
ablation is followed by a state of great depression, loss of appetite, and a 
refusal to take food. 

The centre for sensory impressions is located in the posterior portion of 
the cerebrum; destruction of the posterior portion of the internal capsule 
causes loss of sensation on the opposite side of the body. 


SYMPATHETIC NERVOUS SYSTEM. 


123 


SYMPATHETIC NERVOUS SYSTEM. 

The Sympathetic Nervous System consists of a chain of ganglia 
connected together by longitudinal nerve filaments, situated on each side 
of the spinal column, running from above downward. The two gangli¬ 
onic cords are connected together in the interior of the cranium by the 
ganglion of Ribes, on the anterior communicating artery, and terminate in 
the ganglion impar, situated at the tip of the coccyx. 

The chain of ganglia is divided into groups and named according to the 
localities in which they are found, viz: cranial, four in number; cervical, 
three; thoracic, twelve ; lumbar, five , sacral, five; coccygeal, one. Each 
ganglion consists of a collection of vesicular nervous matter, among which 
are found tubular and gelatinous nerve fibres. The ganglia are reinforced 
by motor and sensory fibres from the cerebro-spinal nervous system. 

The Ganglia are distinct nerve fibres, from which branches are dis¬ 
tributed to glands, arteries, muscles, and to the cerebral and spinal nerves; 
many pass, also, to the visceral ganglia, e. g., cardiac, semilunar, pelvic, etc. 

Cephalic Ganglia. 

1. The Ophthalmic or Ciliary ganglion is situated in the orbital cavity 
posterior to the eyeball; it is of small size, and of a reddish-gray color; 
receives filaments of communication from the motor oculi, ophthalmic 
branch of the 5th pair, and the carotid plexus. Its filaments of distribu¬ 
tion are the ciliary nerves which pass to the iris and ciliary muscle. 

Function. It is the centre through which the reflex acts take place by 
which the pupil is contracted or dilated; controls the movement of 
accommodation for vision at different distances. 

2. The Spheno-palatine , Or Meckel’s ganglion, triangular in shape, is 
situated in the spheno-maxillary fossa; receives filaments from the facial 
(Vidian nerve), and the superior maxillary branch of the 5th nerve. Its 
filaments of distribution pass to the gums, the soft palate, levator palati, 
and azygos uvulae muscles. 

The Otic, or Arnold’s ganglion, is of small size, oval in shape, and 
situated beneath the foramen ovale; receives a motor filament from the 
facial and sensory filaments from the glosso-pharyngeal and 5th nerve; 
sends filaments to the mucous membrane of the tympanic cavity and to the 
tensor tympani muscle. 

4. The Submaxillary ganglion, situated in the sub-maxillary gland, 
receives motor filaments from the chorda tympani and sensory filaments 
from the lingual branch of the 5th nerve. Regulates to some extent the 
secretion of saliva. 


124 


HUMAN PHYSIOLOGY. 


Cervical Ganglia. 

The Superior cervical ganglion is fusiform in shape, of a grayish-red 
color, and situate opposite the 2d and 3d cervical vertebrae; it sends 
branches to form the carotid and cavernous plexuses which follow the 
course of the carotid arteries to their distribution; also sends branches 
to join the glosso-pharyngeal and pneumogastric, to form the pharyngeal 
plexus. 

The Middle cervical ganglion, the smallest of the three, is occasionally 
wanting; it is situated opposite the 5th cervical vertebra; sends branches 
to the superior and inferior cervical ganglion, and to the thyroid artery. 

The Inferior cervical ganglion, irregular in form, is situated opposite the 
last cervical vertebrae ; it is frequently fused with the first thoracic ganglion. 

The superior , middle and inferior cardiac nerves , arising from these 
cervical ganglia, pass downward and forward to form the deep and super¬ 
ficial cardiac plexuses located at the bifurcation of the trachea, from which 
branches are distributed to the heart, coronary arteries, etc. 

The Thoracic Ganglia are usually twelve in number, placed against 
the heads of the ribs behind the pleura; they are small in size and gray in 
color; they communicate with the cerebro-spinal nerves by two filaments, 
one of which is white, the other gray. 

The great splanchnic nerve is formed by the union of branches from the 
sixth, seventh, eighth and ninth ganglia ; it passes through the diaphragm 
to the semi-lunar ganglion. 

The lesser splanchnic nerve is formed by the union of filaments from the 
tenth and eleventh ganglia, and is distributed to the coeliac plexus. 

The renal splanchnic nerve arises from the last thoracic ganglion and 
terminates in the renal plexus. 

The semi-lunar ganglia, the largest of the sympathetic, are situated by 
the side of the coeliac axis ; they send radiating branches to form the solar 
plexus; from the various plexuses, nerves follow the gastric, splenic, 
hepatic, renal, etc., arteries, into the different abdominal viscera. 

The Lumbar Ganglia, four in number, are placed upon the bodies of 
the vertebra; they give off branches which unite to form the aortic lumbar 
plexus and the hypogastric plexus, and follow the blood vessels to their 
terminations. 

The Sacral and Coccygeal Ganglia send filaments of distribution to 
all the blood vessels of the pelvic viscera. 

Properties and Functions. The sympathetic nerve possesses both 
sensibility and the power of exciting motion, but these properties are much 


SYMPATHETIC NERVOUS SYSTEM. 


125 


less decided than in the cerebro-spinal system. Irritation of the ganglia 
does not produce any evidence of pain until some time has elapsed. If 
caustic soda be applied to the semilunar ganglia, or a galvanic current be 
passed through the splanchnic nerves, no instantaneous effect is noticed, as 
in the case of the cerebro-spinal nerves; but in the course of a few seconds 
a slow, progressive contraction of the muscular coat of the intestines is 
established, which continues for some time after the irritation is removed. 
Division of the sympathetic nerve in the neck is followed by a vascular 
congestion of the parts above the section on the corresponding side, attended 
by an increase in the temperature; not only is there an increase in the 
amount of blood, but the rapidity of the blood current is very much 
hastened, and the blood in the veins becomes of a brighter color. Gal¬ 
vanization of the upper end of the divided nerve causes all of the preced¬ 
ing phenomena to disappear; the congestion decreases, the temperature 
falls, and the venous blood becomes dark again. 

The sympathetic exerts a similar influence upon the circulation of the 
limbs and the glandular organs; destruction of the first thoracic ganglion 
and division of the nerves forming the lumbar and sacral plexuses is 
followed by a dilatation of the vessels, an increased rapidity of the circu¬ 
lation, and an elevation of temperature in the anterior and posterior 
limbs; galvanization of the peripheral ends of these nerves causes all of 
these phenomena to disappear. Division of the splanchnic nerve causes a 
dilatation of the blood vessels of the intestine. 

These phenomena of the sympathetic nerve system are dependent upon 
the presence of vaso-motor nerves which, under normal circumstances, 
exert a tonic influence upon the blood vessels. These nerves, derived 
from the cerebro-spinal system, the medulla oblongata, leave the spinal 
cord by the rami communicantes , enter the sympathetic ganglia, and 
finally terminate in the muscular wall of the blood vessels. 

Sleep is a periodical condition of the nervous system, in which there is 
a partial or complete cessation of the activities of the higher nerve centres. 
The cause of sleep is a diminution in the quantity of blood, occasioned by 
a contraction of the smaller arteries under the influence of the vaso-motor 
nerves. 

During the waking state the brain undergoes a physiological waste, as a 
result of the exercise of its functions; after a certain length of time its 
activities become enfeebled, and a period of repose ensues, during which 
a regeneration of its substance takes place. 

When the brain becomes enfeebled there is a diminished molecular 
activity and an accumulation of waste products; under these circumstances 


126 


HUMAN PHYSIOLOGY. 


it ceases to dominate the medulla oblongata and the spinal cord. These 
centres then act more vigorously, and diminish the calibre of the cerebral 
blood vessels through the action of the vaso-motor nerves, producing a con¬ 
dition of physiological anaemia and sleep; during this state waste products 
are removed, force is stored up, nutrition is restored, and waking finally 
occurs. 

THE SENSE OF TOUCH. 

The Sense of Touch is a modification of general sensibility, and 
located in the skin, which is especially adapted for this purpose, on account 
of the number of nerves and papillary elevations it possesses. The struc¬ 
tures of the skin and the modes of terminations of the sensory nerves have 
already been considered. 

The Tactile Sensibility varies in acuteness in different portions of the 
body; being most marked in those regions in which the tactile corpuscles 
are most abundant, e. g., the palmar surface of the third phalanges of the 
fingers and thumb. 

The relative sensibility of different portions of the body has been ascer¬ 
tained by means of a pair of compasses, the points of which are guarded 
by cork, and then determining how closely they could be brought together, 
and yet be felt at two distinct points. The following are some of the 
measurements:— 


Point of tongue...... ^ of a line. 


Palmar surface of third phalanx. 

Red surface of lips. 

Palmar surface of metacarpus. 

Tip of the nose. 

Part of lips covered by skin. 

Palm of hand. 

1 line. 

2 lines. 

3 “ 

3 “ 

4 “ 
s “ 

Lower part of forehead... 

j 

IO “ 

Back of hand.;. 

14 . “ 

Dorsum of foot. 

18 “ 

Middle of the thigh. 

3 ° “ 

The sense of touch communicates to the mind the 

idea of resistance 


only, and the varying degrees of resistance offered to the sensory nerves 
enables us to estimate, with the aid of the muscular sense, the qualities of 
-hardness and softness of external objects. The idea of space or exten¬ 
sion is obtained when the sensory surface or the external object changes its 
place in regard to the other; the character of the surface, its roughness or 
smoothness , is estimated by the impressions made upon the tactile papillae. 













THE SENSE OF TASTE. 


127 


Appreciation of Temperature. —The general surface of the body is more 
or less sensitive to differences of temperature, though this sensation is 
separate from that of touch; whether there are nerves especially adapted 
for the conduction of this sensation has not been fully determined. Under 
pathological conditions, however, the sense of touch may be abolished, 
while the appreciation of changes in temperature may remain normal. 

This cutaneous surface varies in its sensibility to temperature in different 
parts of the body, and depends, to some extent, upon the thickness of the 
skin, exposure, habit, etc.; the inner surface of the elbow is more sensi¬ 
tive to changes in temperature than the outer portion of the arm; the 
left hand is more sensitive than the right; the mucous membrane less so 
than the skin. 

Excessive heat or cold has the same effect upon the sensibility; the 
temperatures most readily appreciated are those between 50° F. and 115 0 F. 

The sensation of pain and tickling appear to be conducted to the brain, 
also, by nerves different from those of touch; in abnormal conditions the 
appreciation of pain may be entirely lost, while touch remains unimpaired. 

THE SENSE OF TASTE. 

The Sense of Taste is localized mainly in the mucous membrane 
covering the superior surface of the tongue. 

The Tongue is situated in the floor of the mouth; its base is directed 
backward, and connected with the hyoid bone, by numerous muscles, with 
the epiglottis and soft palate; its apex is directed forward against the pos¬ 
terior surface of the teeth. 

The substance of the tongue is made up of intrinsic muscular fibres, 
the linguales; it is attached to surrounding parts, and its various move¬ 
ments performed by the extrinsic muscles, e. g., stylo-glossus, genio-hyo- 
glossus, etc. 

The mucous membrane covering the tongue is continuous with that 
lining the commencement of the alimentary canal, and is furnished with 
vascular and nervous papillae. 

The papillae are analogous in their structure to those of the skin, and 
are distributed over the dorsum of the tongue, giving it its characteristic 
roughness. 

There are three principal varieties:— 

I. The filiform papilla are most numerous, and cover the anterior two- 
thirds of the tongue; they are conical or filiform in shape, often prolonged 
into filamentous tufts, of a whitish color, and covered by horny epithelium. 


128 


HUMAN PHYSIOLOGY. 


2. The fungiform papillce are found chiefly at the tip and sides of the 
tongue; they are larger than the preceding, and may be recognized by 
their deep red color. 

3. The circumvallate papillce are rounded eminences, from 8 to 10 in 
number, situated at the base of the tongue, where they form a V-shaped 
figure. They are quite large, and consist of a central projection of 
mucous membrane, surrounded by a wall, or circumvallation, from which 
they derive their name. 

The Taste Beakers, supposed to be the true organs of taste, are flask¬ 
like bodies, ovoid in form, about the 3-^ of an inch in length, situated in 
the epithelial covering of the mucous membrane, on the circumvallate 
papillae. They consist of a number of fusiform, narrow cells, and curved 
so as to form the walls of this flask-like body ; in the interior are elongated 
cells, with large, clear nuclei, the taste cells. 

Nerves of Taste. The chorda tympani nerve, a branch of the facial, 
after leaving the cavity of the tympanum, joins the 3d division of the 5th 
nerve between the two pterygoid muscles, and then passes forward in the 
lingual branches, to be distributed to the mucous membrane of the anterior 
two-thirds of the tongue. Division or disease of this nerve is followed by 
a loss of taste in the part to which it is distributed. 

The glosso-pharyngeal enters the tongue at the posterior border of the 
hyo-glossus muscle, and is distributed to the mucous membrane of the base 
and sides of the tongue, fauces, etc. 

The lingual branch of the trifacial nerve endows the tongue with gene¬ 
ral sensibility; the hypoglossal endows it with motion. 

The nerves of taste in the superficial layer of the mucous membrane 
form a fine plexus from which branches pass to the epithelium and pene¬ 
trate it; others enter the taste beakers, and are directly connected with 
the taste cells. 

The seat of the sense of taste has been shown by experiment to be the 
whole of the mucous membrane over the dorsum of the tongue, soft palate, 
fauces, and upper part of the pharynx. 

The Sense of Taste enables us to distinguish the savor of substances 
introduced into the mouth, which is different from tactile sensibility. The 
sapid quality of substances appreciated by the tongue are designated as 
bitter, sweet, alkaline, sour, salt, etc. 

The Essential Conditions for the production of the impressions of 
taste are (1) a state of solubility of the food ; (2) a free secretion of the 
saliva, and (3) active movements on the part of the tongue, exerting pres- 


THE SENSE OF SMELL. 


129 


sure against the roof of the mouth, gums, etc., thus aiding the solution of 
various articles and their osmosis into the lingual papillae. Sapid sub¬ 
stances, when in a state of solution, pass into the interior of the taste 
beakers and come into contact, through the medium of the taste cells, 
with the terminal filaments of the gustatory nerves. 


THE SENSE OF SMELL. 

The Sense of Smell is located in the mucous membrane lining the 
upper part of the nasal cavity, in which the olfactory nerves are distributed. 

The Nasal Fossae are two cavities, irregular in shape, separated by 
the vomer, the perpendicular plate of the ethmoid bone, and the triangular 
cartilage. They open anteriorly and posteriorly by the anterior and pos¬ 
terior nares, the latter communicating with the pharynx. They are lined 
by mucous membrane, of which the only portion capable of receiving odor¬ 
ous impressions is the part lining the upper one-third of the fossae. 

The Olfactory Nerves, arising by three roots from the posterior and 
inferior surface of the anterior lobes, pass forward to the cribriform plate 
of the ethmoid bone, where they each expand into an oblong body, the 
olfactory bulb. From its under surface from 15 to 20 filaments pass down¬ 
ward through the foramina, to be distributed to the olfactory mucous mem¬ 
brane, where they terminate in long, delicate, spindle-shaped cells, the 
olfactory cells , situated between the ordinary epithelial cells. 

The olfactory bulbs are the centres in which odorous impressions are 
perceived as sensations; destruction of these bulbs being attended by an 
abolition of the sense of smell. 

In animals which possess an acute sense of smell, there is a correspond¬ 
ing increase in the development of the olfactory bulbs. 

The Essential Conditions for the sense of smell are, (1) a special 
nerve centre capable of receiving impressions and transforming them into 
odorous sensations. (2) Emanations from bodies which are in a gaseous 
or vaporous condition. (3) The odorous emanations must be drawn freely 
through the nasal fossae; if the odor be very faint, a peculiar inspiratory 
movement is made, by which the air is forcibly brought into contact with 
the olfactory filaments. The secretions of the nasal fossae probably dis¬ 
solve the odorous particles. 

Various substances, as ammonia, horseradish, etc., excite the sensibility 
of the mucous membrane, which must be distinguished from the perception 
of true odors. 


130 


HUMAN PHYSIOLOGY. 


THE SENSE OF SIGHT. 

The Eyeball. The eyeball, or organ of vision, is situated within the 
orbital cavity, and loosely held in position by the fibrous capsule of Tenon. 
It rests upon a cushion of fat, which never disappears, except in cases of 
extreme starvation; it is protected from injury by the bony orbital walls, 
and is so situated as to permit an extensive range of vision. 

Blood vessels and Nerves. The structures of the eyeball are sup¬ 
plied with blood by the ciliary arteries, which pierce the posterior surface 
around the optic nerve. 

The Ciliary or Ophthalmic ganglion , about the size of a pin’s head, 
situated in the posterior portion of the orbital cavity, receives filaments of 
communication from the trifacial or 5th nerve, the motor oculi or 3d nerve, 
and the sympathetic. From its anterior portion are given off the ciliary 
nerves, which enter the ball posteriorly and are distributed to the structures 
of which it is composed. 

Structure. The form of the eyeball is that of a sphere; it is about 
one inch in the transverse diameter, and a little longer in the antero-posterior 
diameter, on account of its having the segment of a smaller sphere inserted 
into the anterior surface. It is composed of 3 coats; in its interior is con¬ 
tained the refracting apparatus. 

The Sclerotic and Cornea together form the external coat of the eye; 
the former covering the posterior $, the latter covering the anterior 
The sclerotic is a dense, opaque, fibrous membrane, varying in thickness 
from the to the ^ of an inch; it is composed of connective tissue and is 
slightly vascular. Posteriorly it is continuous with the sheath of the optic 
nerve, and is pierced by that nerve, as well as by the ciliary vessels and 
nerves; anteriorly its fibres become quite pale, and after passing into the 
cornea, transparent. It is a protective covering, and gives attachment to 
the tendons of the muscles by which the eyeball is moved. 

The Cornea is a non-vascular, transparent membrane, composed for the 
most part of connective tissue in which are contained stellate corpuscles 
filled with a clear fluid. It is covered anteriorly by the basement mem¬ 
brane of the conjunctiva, upon which rests several layers of epithelial 
cells; posteriorly it is lined by the membrane of Descemet, which is re¬ 
flected on to the anterior surface of the iris. 

The Choroid, the Iris, the Ciliary Muscle and Ciliary Processes, 
together constitute the middle coat of the eye. 

The Choroid coat , about the ^ of an inch in thickness, is both a vas- 


THE SENSE OF SIGHT. 


131 


cular and pigmentary membrane; it is of a dark brown color externally, 
and of a deep black internally. 

The outer portion is made up of a rich network of vessels, the branches 
of the ciliary arteries and veins; the inner portion, the pigmentary layer, 
is a delicate membrane formed of hexagonal cells, containing black pig¬ 
ment. 

The Function of the choroid is mainly to absorb the rays of light which 
pass through the retina, and thus prevent them from interfering with the 
distinctness of vision by being again reflected upon the retina. 

The Iris is a circular, muscular diaphragm, placed in the anterior por- 


a 

b 


c 


d 


SCLEROTIC COAT REMOVED TO SHOW THE CHOROID, CILIARY MUSCLE AND NERVES. 

a. Sclerotic coat. b. Veins of the choroid, c Ciliary nerves, d. Veins of the choroid. 
e. Ciliary body. /. Iris .—From Holden’s Anatomy. 

tion of the eye, and perforated a little to the nasal side of the centre by a 
circular opening, the pupil; it is attached by its periphery to the point of 
junction of the sclerotic and cornea. It is composed of a connective tissue 
stroma, blood vessels and non-striated muscular fibres, circular and radiat¬ 
ing. The circular fibres surround the margin of the pupil like a sphincter, 
and are controlled by the 3d pair of nerves; the radiating fibres (dilators 
of the pupil) radiate from the centre toward its circumference, and' are 
controlled by the sympathetic system of nerves. 

The Ciliary muscle is a grayish circular band, consisting of unstriped 
muscular fibres, about one-eighth of an inch long, running from before 


Fig. 11. 










132 


HUMAN PHYSIOLOGY. 


backward; beneath the radiating fibres are small bands of circular fibres 
running around the eye. It arises from the line of junction of the sclerotic, 
cornea and iris; passing backward it is attached to the outer surface of 
the choroid; it is the principal agent in accommodation, and innervated 
by the 3d pair of nerves. 

The Retina forms the internal coat of the eye; in the fresh state it is a 
delicate, transparent membrane, but soon becomes opaque and of a pinkish 
tint; it extends forward almost to the ciliary processes, where it terminates 
in the ora serrata. In the posterior portion of the retina, at a point cor¬ 
responding to the axis of vision, is a rounded, elevated yellow spot, the 
limbus luteus , having a central depression, the fovea centralis; about tV 
of an inch to the inner side is the point of entrance of the optic nerve, 
where it spreads out to assist in the formation of the retina. The arteria 
centralis retina pierces the optic nerve near the sclerotic, runs forward in 
its substance and is distributed in the retina as far forward as the ciliary 
processes. 

The Retina consists of nine distinct layers, from within outward, sup¬ 
ported by connective tissue. 1. Membrana limitans interna. 2. Fibres 
of optic nerve. 3. Layers of ganglionic corpuscles. 4. Molecular layer. 
5. Internal granular layer. 6. Molecular layer. 7. External granular 
layer. 8. Membrana limitans externa. 9. Layer of rods and cones. 

In the Fovea centralis , at the point of most distinct vision, all of the 
layers disappear except the layer of rods and cones, which becomes some¬ 
what longer and more slender. 

The Aqueous humor is a clear fluid, alkaline in reaction, occupying the 
anterior chamber of the eye; this chamber is bounded in front by the 
cornea, posteriorly by the iris. 

The Vitreous humor forms about four-fifths of the entire ball. It sup¬ 
ports the retina, and is excavated anteriorly for the reception of the lens; 
it is transparent, of a jelly-like consistence, and surrounded by a structure¬ 
less, transparent membrane, the hyaloid membrane. 

The Crystalline lens is situated immediately behind the pupil, in the 
concavity of the vitreous humor. It is inclosed in a highly elastic, trans¬ 
parent membrane, the capsule. The lens is a transparent, doubly-convex 
body, i/£ of an inch transversely, ^ of an inch antero-posteriorly; it is 
held in position by the suspensory ligament, formed by a splitting of the 
hyaloid tunic, the external layer of which passes in front of the lens, the 
internal layer behind it. Its function is to refract the rays of light and 
bring them to a focus upon the retina. 


THE SENSE OF SIGHT. 


133 


Vision. The eye may be regarded as a camera obscura, in which 
images of external objects are thrown upon a screen, the retina, by means 
of a double convex lens. 

The Essential Conditions for proper vision are : i. Certain refract¬ 
ing media, e. g., cornea, aqueous humor, and crystalline lens, by which 
the rays of light are so disposed as to form an image. 2. A diaphragm , 
the iris, which, by alternately contracting and dilating, increases or dimin¬ 
ishes the amount $f light entering the eye. 3. A sensitive surface, to 


Fig. 12. 



DIAGRAM OF A VERTICAL SECTION OF THE EYE. 

1. Anterior chamber filled with aqueous humor. 2. Posterior chamber. 3. Canal ot 
Petit. 

a. Hyaloid membrane, b. Retina (dotted line), c. Choroid coat (black line). 
d. Sclerotic coat. e. Cornea. /. Iris. g. Ciliary processes, h. Canal of Schlemm 
or Fontana, i. Ciliary muscle. {From Holden's Anatomy .) 

receive the image and transmit the luminous impressions through the optic 
nerve to the brain. 4. A contractile structure, the ciliary muscle, which 
can so manipulate the lens as to enable external objects to be seen at near 
or far distances. 

The Refracting Apparatus, by which parallel rays of light are brought 
to a focus on the retina, consists mainly of the crystalline lens, though 
aided by the cornea and aqueous humor. A ray of light passing through 
the pupil is refracted and concentrated by the lens at a given point pos- 












134 


HUMAN PHYSIOLOGY. 


terior to it. For the correct perception of images of external objects, the 
rays of light must be accurately focused on the retina; in order that this 
may be accomplished, the lens must have a certain density and a proper 
curvature of its surfaces. When the lens is too convex, its refracting power 
is greatly increased, the rays of light are brought to a focus in front of the 
retina, and the visual perception becomes dim and confused. When it is too 
flat, the rays are not focused at all, and the resulting perception is the same. 

The Crystalline lens , therefore, produces a distinct perception of the 
outline and form of external objects. 

Action of the Iris. The iris, consisting of contracting and dilating 
fibres, transmits and regulates the quantity of light passing through its 
central aperture, the pupil, which is necessary for distinct vision. 

If the light be too intense or excessive, the circular fibres contract under 
the stimulus of the 3d pair of nerves, and the aperture is diminished in 
size; if the quantity of light be insufficient, the dilating fibres contract 
under the stimulus of the sympathetic, and the pupillary aperture is 
increased in size. 

The Retina, which is formed partly by the expansion of the optic 
nerve, and partly by new nervous structures, is the membrane which 
receives the impressions of light. Its posterior surface, which is in con¬ 
tact with the choroid, and especially the layer of rods and cones, is the 
sensitive portion, in which the rays of light produce their effects. 

The point of most distinct vision is in the macula lutea, and especially 
in its central depression, the fovea, which corresponds to the central axis 
of the eye; it is situated about tV of an inch to the outside of the 
entrance of the optic nerve. It is at this point that images of external 
objects are seen most distinctly, while all around it the perceptions are 
more or less obscure; at the macula all the layers disappear except the 
layer of rods and cones. 

Blind Spot. At the point of entrance of the optic nerve is a region 
in which the rays of light make no impression, owing to the absence of 
the proper retinal elements; the fibres of the optic nerve being insensible 
to the action of light. 

The course which a ray of light takes is as follows: After passing 
through the cornea, lens, and vitreous humor and the layers of the retina, 
it is finally arrested by the pigmentary layer of the choroid ; here it excites 
in the layer of rods and cones some physical or chemical change, which 
is then transmitted to the fibres of the optic nerve, and thence to the brain, 
where it is perceived as a sensation of light. 


THE SENSE OF SIGHT. 


135 




The Accommodation of the eye to vision for different distances is 
accomplished by a change in the convexities of the lens, caused by the 
action of the ciliary muscle. When the eye is accommodated for vision at 
far distances, the structures are in a passive condition and the lens is flat¬ 
tened ; when it is adjusted for vision at short distances, the convexities of 
the lens are increased. 

When the Ciliary muscle contracts and draws the choroid coat forward, 
the suspensory ligament is relaxed and the lens becomes more convex, in 
virtue of its own elasticity. 

Optical Defects. Astigmatism is a condition of the eye which pre¬ 
vents vertical and horizontal lines from being focused at the same time, 
and is due to a greater curvature of the eye in one direction than 
another. 

Spherical aberration is a condition in which there is an indistinctness 
of an image from the unequal refraction of the rays of light passing 
through the circumference and the centre of the lens; it is corrected 
mainly by the iris, which cuts off the marginal rays, and only transmits 
those passing through the centre. 

Chromatic aberration , in which the image is surrounded by a colored 
margin, from the decomposition of the rays of light into their elementary 
parts, is corrected by the different refractive powers of the transparent 
media in front of the retina. 

Myopia , or short-sightedness , is caused by an abnormal increase in the 
antero-posterior diameter of the eyeball; the lens being too far removed 
from the retina, forms the image in front of it, and the perception becomes 
dim and blurred. Concave glasses correct this defect, by preventing the 
rays from converging too soon. 

Hypermetropia , or long-sightedness , is caused by a shortening of the 
antero-posterior diameter; the lens consequently focuses the rays of light 
behind the retina. Convex glasses correct this defect, by converging the 
rays of light more anteriorly. 

Presbyopia is a loss of the power of accommodation of the eye to near 
objects, and usually occurs between the ages of 40 and 60; it is remedied 
by the use of a convex eye-glass. 

Accessory Structures. The muscles which move the eyeball are 
six in number; the superior and inferior recti, the external and internal 
recti, the superior and inferior oblique muscles. The four recti muscles, 
arising from the apex of the orbit, pass forward and are inserted into the 
sides of the sclerotic coat; the superior and inferior muscles rotate the 


136 


HUMAN PHYSIOLOGY. 


eye around a horizontal axis; the external and internal rotate it around 
a vertical axis. 

The Superior oblique muscle, having the same origin, passes forward to 
the inner and upper angle of the orbital cavity, where its tendon passes 
through a cartilaginous pulley; it is then reflected backward and inserted 
into the sclerotic just behind the transverse diameter. Its function is to 
rotate the eyeball in such a manner as to direct the pupil downward and 
outward. 

The inferior oblique muscle arises at the inner angle of the orbit and 
then passes outward and backward to be inserted into the sclerotic. Its 
function is to rotate the eyeball and direct the pupil upward and outward. 

By the associated action of all these muscles, the eyeball is capable of 
performing all the varied and complex movements necessary for distinct 
vision. 

The Eyelids, bordered with short, stiff hairs, shade the eye and protect 
it from injury. On the posterior surface, just beneath the conjunctiva, are 
the Meibomian glands, which secrete an oily fluid; it covers the edge of 
the lids and prevents the tears from flowing over the cheek. 

The Lachrymal Glands are ovoid in shape and situated at the upper 
and outer part of the orbital cavity; they open by from six to eight ducts 
at the outer portion of the upper lids. 

The Tears, secreted by the lachrymal glands, are distributed over the 
cornea by the lids during the act of winking, and keep it moist and free 
from dust. The excess of tears passes into the lachrymal ducts, which 
begin by two minute orifices, one on each lid, at the inner canthus. They 
conduct the tears into the nasal duct, and so into the nose. 


THE SENSE OF HEARING. 

The Organ of Hearing is situated in the petrous portion of the tem¬ 
poral bone, and is divided into three portions, viz: the external ear, the 
middle ear and the internal ear. 

The External Ear consists of two portions, the pinna or auricle, and 
the external auditory canal. The former, consisting of cartilage, which is 
irregularly folded and covered by integument, is united to the side of the head 
by ligaments and muscles; the latter, partly cartilaginous and partly bony, 
is about one and a quarter inches in length ; it runs downward and forward 
from the concha to the middle ear, and is lined by a reflection of the gene¬ 
ral integument, in which is lodged a number of glands, which secrete the 
cerumen. 


THE SENSE OF HEARING. 


137 


The function of the external ear is to collect the waves of sound coming 
from all directions and to transmit them to the membrana tympani. 

The Middle Ear or Tympanum is an irregularly shaped cavity, 
narrow from side to side, but long in its vertical and antero-posterior 
diameters. 

It is separated from the external ear by the membrana tympani , and 
from the internal ear by a second membrana tympani; it communicates 
posteriorly with the mastoid cells, anteriorly with the pharynx, through 
the Eustachian tube. It is lined by mucous membrane, and contains three 
small bones, forming a connected chain running across its cavity. 

The Membrana tympani is a thin, delicate, translucent membrane, cir¬ 
cular in shape and measuring about two-fifths of an inch in diameter; it is 
received into a delicate ring of bone, which in the adult becomes consoli¬ 
dated with the temporal bone; it is concave externally and situated ob¬ 
liquely, inclining at an angle of 45 degrees. 

The membrane consists of three layers; the outer is formed by a reflec¬ 
tion of the integument lining the external auditory canal; the middle is 
composed of fibrous tissue, and the internal of mucous membrane. 

The Function of the membrana tympani is to receive and transmit the 
waves of sound to the chain of bones; it is capable of being made tense 
and lax by the action of the tensor tympani and laxator tympani muscles, 
so as to vibrate in unison with the waves of sound in the external auditory 
meatus. When the membrane is relaxed, its vibrations have a greater 
amplitude, and it appreciates sounds of a low pitch. When it is made 
tense it vibrates less forcibly and appreciates sounds of a high pitch. 

The Chain of bones is formed by the malleus, incus and stapes, united 
together by ligaments. The malleus consists of a head, neck and handle, 
of which the latter is attached to the inner surface of the membrana tym¬ 
pani. The incus , or anvil bone, articulates with the head of the malleus 
by a capsular joint, and with the stapes by the end of its long process. 
The stapes resembles a stirrup in shape; it articulates externally with the 
long process of the incus, and internally its oval base is applied to the 
edges of the foramen ovale. 

The Function of the chain of bones is to transmit the waves of sound 
across the tympanum to the internal ear; being surrounded by air, and 
acting as a solid rod, they prevent the vibrations from losing but little in 
intensity. 

The Tensor tympani muscle arises mainly from the cartilaginous part 
of the Eustachian tube ; it then passes backward into the tympanic cavity, 
where it bends at a right angle around a process of bone, and is inserted 
J 


138 


HUMAN PHYSIOLOGY. 


into the root of the handle of the malleus. Its function is to draw the 
handle of the malleus internally, and thus increase the tension of the 
membrana tympani, so as to make it capable of vibrating with sounds of 
greater or less intensity; at the same time it tightens the joints of the 
chain of bones, so that they may the better conduct waves of sound to the 
internal ear, with but a slight loss of intensity. 

The Laxator tympani muscle , arising from the spinous process of the 
sphenoid bone, passes backward through the Glasserian fissure, into the 
tympanic cavity, and is inserted into the neck of the malleus. Its function 
is to draw the handle of the malleus outward, and so relax the membrana 
tympani, and enable it to receive waves of sound of greater amplitude 
than when it is tense. 

The Stapedius muscle , emerging from the cavity of the pyramid of bone 
projecting from the posterior wall of the tympanum, is inserted into the 
head of the stapes bone. Its function is to draw the stapes backward, 
preventing too great movement of the bone, and at the same time relaxing 
the membrana tympani. 

The Eustachian tube , by means of which the middle ear communicates 
with the pharynx, is partly bony and partly cartilaginous in its structure. 
It is about one and a half inches in length; commencing at its opening in 
the pharynx, it passes upward and outward to the spine of the sphenoid 
bone, where it is slightly contracted; it then gradually dilates as it passes 
backward into the tympanic cavity. It is lined by mucous membrane, 
which is continued into the middle ear and into the mastoid cells. 

The Eustachian tube permits the passage of air from the pharynx into 
the middle ear; in this way the pressure of the air within and without the 
membrana tympani is equalized, which is one of the essential conditions 
for the reception of sonorous vibrations. 

By closing the mouth and nose, and blowing out the cheeks, air can be 
forced into the middle ear, producing undue pressure and bulging out of 
the membrana tympani; by making an effort at swallowing, with the mouth 
and nose closed, the air in the tympanum can be rarefied and the tympanic 
membrane will be pressed in. In both such cases the acuteness of hearing 
is very much diminished. 

The pharyngeal orifice of the Eustachian tube is opened by the action of 
certain of the muscles of deglutition, viz. : the levator palati, tensor palati, 
and at times the palato-pharyngei muscles. 

The Internal Ear, or Labyrinth, is located in the petrous portion 
of the temporal bone, and consists of an osseous and membranous 
portion. 


THE SENSE OF HEARING. 139 

The Osseous Labyrinth is divisible into three parts, viz.: the vesti¬ 
bule, the semi-circular canals and the cochlea. 

The Vestibule is a small, triangular cavity, which communicates with 
the middle ear by the foramen ovale; in the natural condition it is closed 
by the base of the stapes bone. The filaments of the auditory nerve enter 
the vestibule through small foramina in the inner wall, at the fovea hemi- 
spherica. 

The Semi-circular canals are three in number: the superior vertical, 
the inferior vertical and the horizontal, each of which opens into the cavity 
of the vestibule by two openings, with the exception of the two vertical, 
which at one extremity open by a common orifice. 

The Cochlea forms the anterior part of the internal ear. It is a gradu¬ 
ally tapering canal, about one and a half inches in length, which winds 
spirally around a central axis, the modiolus , two and a half times. The 
interior of the cochlea is partly divided into two passages by a thin plate of 
bone, the lamina osseous spiralis , which projects from the central axis two- 
thirds across the canal. These passages are termed the scala vestibuli and 
the scala tympani , from their communication with the vestibule and tym¬ 
panum. The scala tympani communicates with the middle ear through 
the foramen rotundum , which, in the natural condition, is closed by the 
second membrana tympani; superiorly they are united by an opening, the 
helicotrema. 

The whole interior of the labyrinth, the vestibule, the semi-circular 
canals, and the scala of the cochlea, contains a clear, limpid fluid, the 
peri lymph , secreted by the periosteum lining the osseous walls. 

The Membranous Labyrinth corresponds to the osseous labyrinth 
with respect to form, though somewhat smaller in size. 

The Vestibular portion consists of two small sacs, the utricle and saccule. 

The Semi-circular canals communicate with the utricle in the same 
manner as the bony canals communicate with the vestibule. The saccule 
communicates with the membranous cochlea by the canalis reuniens. In 
the interior of the utricle and saccule, at the entrance of the auditory 
nerve, are small masses of carbonate of lime crystals, constituting the 
otoliths. Their function is unknown. 

The Membranous cochlea is a closed tube, commencing by a blind 
extremity at the first turn of the cochlea, and terminating at its apex by a 
blind extremity also. It is situated between the edge of the osseous lamina 
spiralis and the outer wall of the bony cochlea, and follows it in its turns 
around the modiolus. 

A transverse section of the cochlea shows that it is divided into two 


140 


HUMAN PHYSIOLOGY. 


portions by the osseous lamina and the basilar membrane: i. The 
scala vestibuli, bounded by the periosteum and membrane of Reissner. 
2 . The scala tympani , occupying the inferior portion, and bounded 
above by the septum, composed of the osseous lamina and the membrana 
basilaris. 

The true membranous canal is situated between the membrane of Reiss¬ 
ner and the basilar membrane. It is triangular in shape, but is partly 
divided into a triangular portion and a quadrilateral portion by the tectorial 
membrane. 

The Organ of Corti is situated in the quadrilateral portion of the canal, 
and consists of pillars or rods, of the consistence of cartilage. They are 
arranged in two rows; the one internal, the other external; these rods rest 
upon the basilar membrane; their bases are separated from each other, bu 
their upper extremities are united, forming an arcade. In the internal row 
it is estimated there are about 3500, and in the external row about 5200 of 
these rods. 

On the inner side of the internal row is a single layer of elongated hair 
cells; on the outer surface of the external row are three such layers of 
hair cells. Nothing definite is known as to their function. 

The Endolymph occupies the interior of the utricle, saccule, membranous 
canals, and bathes the structures in the interior of the membranous cochlea, 
throughout its entire extent. 

The Auditory Nerve at the bottom of the internal auditory meatus 
divides into (1) a vestibular branch, which is distributed to the utricle and 
semi-circular canals; (2) a cochlear branch, which passes into the central 
axis at its base, and ascends to its apex ; as it ascends, fibres are given off, 
which pass between the plates of the osseous lamina, to be ultimately con¬ 
nected with the organ of Corti. 

The Function of the semi-circular canals appears to be to assist in main¬ 
taining the equilibrium of the body; destruction of the vertical canal is 
followed by an oscillation of the head upward and downward; destruc¬ 
tion of the horizontal canal is followed by oscillations from left to right. 
When the canals are injured on both sides, the animal loses the power of 
maintaining equilibrium upon making muscular movements. 

Function of the Cochlea. It is regarded as possessing the power of 
appreciating the quality of pitch and the shades of different musical 
tones. The elements of the organ of Corti are analogous, in some re¬ 
spects, to a musical instrument, and are supposed, by Helmholtz, to be 
tuned so as to vibrate in unison with the different tones conveyed to the 
internal ear. 


VOICE AND SPEECH. 


141 


Summary. The waves of sound are gathered together by the pinna 
and external auditory meatus, and conveyed to the membrana tympani. 
This membrane, made tense or lax by the action of the tensor tympani 
and laxator tympani muscles, is enabled to receive sound waves of either 
a.high or low pitch. The vibrations are conducted across the middle ear 
by the chain of bones to the foramen ovale, and by the column of air of 
the tympanum to the foramen rotundum, which is closed by the second 
membrana tympani; the pressure of the air in the tympanum being regu¬ 
lated by the Eustachian tube. 

The internal ear finally receives the vibrations which excite vibrations 
successively in the perilymph, the walls of the membranous labyrinth, the 
endolymph, and, lastly, the terminal filaments of the auditory nerve, by 
which they are conveyed to the brain. 


VOICE AND SPEECH. 

The Larynx is the organ of voice. Speech is a modification of voice, 
and is produced by the teeth and the muscles of the lips and tongue, co¬ 
ordinated in their action by stimuli derived from the cerebrum. 

The Structures entering into the formation of the larynx are mainly 
the thyroid , cricoid and arytenoid cartilages; they are so situated and 
united by means of ligaments and muscles as to form a firm cartilaginous 
box. The Larynx is covered externally by fibrous tissue and lined inter¬ 
nally with mucous membrane. 

The Vocal Cords are four ligamentous bands, running antero-posteri- 
orly across the upper portion of the larynx, and are divided into the two 
superior or false vocal cords, and the two inferior or true vocal cords; 
they are attached anteriorly to the receding angle of the thyroid cartilages 
and posteriorly to the anterior part of the base of the arytenoid cartilages.* 
The space between the true vocal cords is the rima glottidis. 

The Muscles which have a direct action upon the movements of the 
vocal cords are nine in number, and take their names from their points of 
origin and insertion, viz : the two crico-thyroid, two thyro-arytenoid, two 
posterior crico-arytenoid, two lateral crico arytenoid , and one arytenoid 
muscles. 

The crico-thyroid muscles, by their contraction, render the vocal cords 
more tense by drawing down the anterior portion of the thyroid cartilage 
and approximating it to the cricoid, and at the same time tilting the 
posterior portion of the cricoid and arytenoid cartilages backward. 


142 


HUMAN PHYSIOLOGY. 


The thyro-arytenoid, by their contraction, relax the vocal cords by draw¬ 
ing the arytenoid cartilage forward and the thyroid backward. 

The posterior crico-arytenoid muscles, by their contraction rotate the 
arytenoid cartilages outward and thus separate the vocal cords and enlarge 
the aperture of the glottis. They principally aid the respiratory move¬ 
ments during inspiration. 

The lateral crico-arytenoid muscles are antagonistic to the former, and 
by their contraction rotate the arytenoid cartilages so as to approximate 
the vocal cords and constrict the glottis. 

The arytenoid muscle assists in the closure of the aperture of the glottis. 

The inferior laryngeal nerve animates all the muscles of the larynx, 
with the exception of the crico-thyroid. 

Movements of the Vocal Cords. During respiration the move¬ 
ments of the vocal cords differ from those occurring during the production 
of voice. 

At each inspiration, the true vocal cords are widely separated, and the 
aperture of the glottis is enlarged by the action of the crico-arytenoid 
muscles, which rotate outward the anterior angle of the base of the aryte¬ 
noid cartilages; at each expiration the larynx becomes passive; the 
elasticity of the vocal cords returns them to their original position, and the 
air is forced out by the elasticity of the lungs and the walls of the thorax. 

Phonation. As soon as phonation is about to be accomplished a marked 
change in the glottis is noticed with the aid of the laryngoscope. The 
true vocal cords suddenly become approximated and are made parallel, 
giving to the glottis the appearance of a narrow slit, the edges of which 
are capable of vibrating accurately and rapidly; at the same time their 
tension is much increased. 

With the vocal cords thus prepared, the expiratory muscles force the 
•column of air into the lungs and trachea through the glottis, throwing the 
edges of the cords into vibration. 

The pitch of sounds depends upon the extent to which the vocal cords 
are made tense and the length of the aperture through which the air 
passes. In the production of sounds of a high pitch the tension of the 
vocal cords becomes very marked, and the glottis diminishes in length. 
When grave sounds, having a low pitch, are emitted from the larynx, the 
vocal cords are less tense and their vibrations are large and loose. 

The quality of voice depends upon the length, size and thickness of the 
cords, and the size, form and construction of the trachea, larynx and the 
resonant cavities of the pharynx, nose and mouth. 


VOICE AND SPEECH. 


143 


The compass of the voice comprehends from two to three octaves. The 
range is different in the two sexes; the lowest note of the male being about 
one octave lower than the lowest note of the female; while the highest 
note of the male is an octave less than the highest of the female. 

The varieties of voices, e. g., bass, baritone, tenor, contralto, mezzo- 
soprano and soprano, are due to the length of the vocal cords; being 
longer when the voice has a low pitch, and shorter when it has a high pitch. 

Speech is the faculty of expressing ideas by means of combination of 
sounds, in obedience to the dictates of the cerebrum. 

Articulate sounds may be divided into vowels and consonants. The 
vowel sounds , a , e, i, o, u, are produced in the larynx by the vocal cords. 
The consonantal sounds are produced in the air passages above the larynx 
by an interruption of the current of air by the lips, tongue and teeth; the 
consonants may be divided into : (i) mutes, b, d , k,p, t, c, g; (2) dentals, 
d,j. s, t , z; (3) nasals, m, n , ngj (4) labials, b,p,f> v , m; (5) gutturals, 
k, g, c, and g hard; (6) liquids, /, m, n , r. 


144 


HUMAN PHYSIOLOGY. 


REPRODUCTION. 

Reproduction is the function by which the species is preserved, and is 
accomplished by the organs of generation in the two sexes. 

GENERATIVE ORGANS OF THE FEMALE. 

The Generative Organs of the Female consist of the ovaries, Fal¬ 
lopian tubes, uterus and vagina. 

The Ovaries are two small, ovoid, flattened bodies, measuring one 
inch and a half in length and three-quarters of an inch in width; they are 
situated in the cavity of the pelvis, and imbedded in the posterior layer of 
the broad ligament; attached to the uterus by a round ligament, and to 
the extremities of the Fallopian tubes by the fimbriae. The ovary consists 
of an external membrane of fibrous tissue, the cortical portion, in which 
are imbedded the Graafian vesicles , and an internal portion, the stroma, 
containing blood vessels. 

The Graafian Vesicles are exceedingly numerous, but situated only 
in the cortical portion. Although the ovary contains the vesicles from 
the period of birth, it is only at the period of puberty that they attain their 
full development. From this time onward to the catamenial period, there 
is a constant growth and maturation of the Graafian vesicles. They consist 
of an external investment, composed of fibrous tissue and blood vessels, in 
the interior of which is a layer of cells forming the membrana granulosa ; 
at its lower portion there is an accumulation of cells, the proligerous disc, 
in which the ovum is contained. The cavity of the vesicle contains a 
slightly yellowish, alkaline, albuminous fluid. 

The Ovum is a globular body, measuring about the of an inch in 
diameter; it consists of an external investing membrane, the vitelline mem¬ 
brane, a central granular substance, the vitellus, or yelk , a nucleus, the 
germinal vesicle, in the interior of which is imbedded the nucleolus, or 
germinal spot. 

The Fallopian Tubes are about four inches in length, and extend 
outward from the upper angles of the uterus, between the folds of the 
broad ligaments, and terminate in a fringed extremity, which is attached 
by one of the fringes to the ovary. They consist of three coats: (i) the 
external, or peritoneal, (2) middle, or muscular, the fibres of which are 
arranged jn a circular or longitudinal direction, (3) internal, or mucous, 


GENERATIVE ORGANS OF THE FEMALE. 


145 


covered with ciliated epithelial cells, which are always waving from the 
ovary toward the uterus. 

The Uterus is pyriform in shape, and may be divided into a body 
and neck; it measures about three inches in length and two inches in 
breadth in the unimpregnated state. At the lower extremity of the neck 
is the os externum ; at the junction of the neck with the body is a constric¬ 
tion, the os internum. The cavity of the uterus is triangular in shape, the 
walls of which are almost in contact. 

The walls of the uterus are made up of several layers of non-striated 
muscular fibres, covered externally by peritoneum, and lined internally by 
mucous membrane, containing numerous tubular glands, and covered by 
ciliated epithelial cells. 

The Vagina is a membranous canal, from five to six inches in length, 
situated between the rectum and bladder. It extends obliquely upward 
from the surface, almost to the brim of the pelvis, and embraces at its 
upper extremity the neck of the uterus. 

Discharge of the Ovum. As the Graafian vesicle matures, it in¬ 
creases in size, from an augmentation, of its liquid contents, and approaches 
the surface of the ovary, where it forms a projection, measuring from one- 
fourth to one-half an inch in size. The maturation of the vesicle occurs 
periodically, about every twenty-eight days, and is attended by the phe¬ 
nomena of menstruation. During this period of active congestion of the 
reproductive organs the Graafian vesicle ruptures, the ovum and liquid 
contents escape, and are caught by the fimbriated extremity of the Fallo¬ 
pian tube, which has adapted itself to the posterior surface of the ovary. 
The passage of the ovum through the Fallopian tube into the uterus occu¬ 
pies from ten to fourteen days, and is accomplished by muscular contraction 
and the action of the ciliated epithelium. 

Menstruation is a periodical discharge of blood from the mucous 
membrane of the uterus, due to a fatty degeneration of the small blood 
vessels. Under the pressure of an increased amount of blood in the repro¬ 
ductive organs, attending the process of ovulation, the blood vessels 
rupture, and a hemorrhage takes place into the uterine cavity; thence it 
passes into the vagina, where it is kept in a fluid condition from admixture 
with the vaginal mucus. Menstruation lasts from five to six days, and the 
amount of blood discharged averages about five ounces. 

Corpus Luteum. For some time anterior to the rupture of a Graa¬ 
fian vesicle, it increases in size and becomes vascular; its walls become 
thickened, from the deposition of a reddish-yellow, glutinous substance, a 


146 


HUMAN THYSIOLOGY. 


product of cell growth from the proper coat of the follicle and the membrana 
granulosa. After the ovum escapes, there is usually a small effusion of 
blood into the cavity of the follicle, which soon coagulates, loses its coloring 
matter, and acquires the characteristics of fibrin, but it takes no part in the 
formation of the corpus luteum. The walls of the follicle become convo¬ 
luted, vascular, and undergo hypertrophy, until they occupy the whole of 
the follicular cavity. At its period of fullest development, the corpus 
luteum measures three-fourths of an inch in length and one-half inch in 
depth. In a few weeks the mass loses its red color, and becomes yellow, 
constituting the corpus luteum ox yellow body. It then begins to retract, 
and becomes pale; and at the end of two months nothing remains but a 
small cicatrix upon the surface of the ovary. Such are the changes in the 
follicle, if the ovum has not been impregnated. 

The corpus luteum, after impregnation has taken place, undergoes a much 
slower development, becomes larger, and continues during the entire 
period of gestation. The differences between the corpus luteum of the 
unimpregnated and pregnant condition is expressed in the following table 
by Dalton :— 


At the end of 
three weeks. 
One month. 


Two months. 


Four months. 


Six months. 


Nine months. 


Corpus Luteum of Menstruation. Corpus Luteum of Pregnancy. 

Three-quarters of an inch in diameter; central clot 
reddish; convoluted wall pale. 


Smaller; convoluted 
wall bright yellow; clot 
still reddish. 

Reduced to the condi¬ 
tion of an insignificant 
cicatrix. 

Absent or unnotice- 
able. 


Absent. 


Absent. 


Larger; convoluted wall 
bright yellow; clot still red¬ 
dish. 

Seven-eighths of an inch 
in diameter; convoluted wall 
bright yellow; clot perfectly 
decolorized. 

Seven-eighths of an inch 
in diameter; clot pale and 
fibrinous; convoluted wall 
dull yellow. 

Still as large as at the end 
of second month; clot fibrin¬ 
ous ; convoluted wall paler. 

Half an inch in diameter; 
central clot converted into a 
radiating cicatrix; external 
wall tolerably thick and 
convoluted, but without any 
bright yellow color. 




GENERATIVE ORGANS OF THE MALE. 


147 


GENERATIVE ORGANS OF THE MALE. 

The Generative Organs of the Male consist of the testicles, vasa 
deferentia, vesiculae seminales and penis. 

The Testicles, the essential organs of reproduction in the male, are 
two oblong glands, about an inch and a half in length, compressed from 
side to side, and situated in the cavity of the scrotum. 

The proper coat of the testicle, the tunica albuginea , is a white, fibrous 
structure, about the is of an inch in thickness; after enveloping the testicle, 
it is reflected into its interior at the posterior border, and forms a vertical 
process, the mediastinum testes , from which septa are given off, dividing the 
testicle in lobules. 

The substance of the testicle is made up of the seminiferous tubules , 
which exist to the number of 840; they are exceedingly convoluted, and 
when unraveled, are about 30 inches in length. As they pass toward the 
apices of the lobules they become less convoluted and terminate in from 20 
to 30 straight ducts, the vasa recta , which pass upward through the medias¬ 
tinum and constitute the rete testis. At the upper part of the mediastinum 
the tubules unite to form from 9 to 30 small ducts, the vasa efferentia , which 
become convoluted, and form the globus major of the epididymis; the 
continuation of the tubes downward behind the testicle and a second con¬ 
volution constitutes the body and globus minor. 

The seminal tubule consists of a basement membrane lined by granular 
nucleated epithelium. 

The Vas Deferens, the excretory duct of the testicle, is about two 
feet in length, and may be traced upward from the epididymis to the under 
surface of the base of the bladder, where it unites with the duct of the vesi- 
cula seminalis, to form the ejaculatory duct. 

The Vesiculae Seminales are two lobulated, pyriform bodies, about 
two inches in length, situated on the under surface of the bladder. 

They have an external fibrous coat, a middle muscular coat, and an in¬ 
ternal mucous coat, covered by epithelium, which secretes a mucous fluid. 
The vesiculae seminales serve as reservoirs, in which the seminal fluid is 
temporarily stored up. 

The Ejaculatory Duct, about of an inch in length, opens into the 
urethra, and is formed by the union of the vasa deferentia and the ducts 
of the vesiculae seminales. 

The Prostate Gland surrounds the posterior extremity of the urethra, 
and opens into it by from twenty to thirty openings, the orifices of the pros- 


148 


HUMAN PHYSIOLOGY. 


tatic tubules. The gland secretes a fluid which forms part of the semen, 
and assists in maintaining the vitality of the spermatozoa. 

Semen is a complex fluid, made up of the secretions from the testicles, 
the vesiculse seminales, the prostatic and urethral glands. It is grayish- 
white in color, mucilaginous in consistence, of a characteristic odor, and 
somewhat heavier than water. From half a drachm to a drachm is ejacu- 
lated at each orgasm. 

The Spermatozoa are peculiar anatomical elements, developed within 
the seminal tubules, and possess the power of spontaneous movement. 
The spermatozoa consist of a conoidal head and a long filamentous tail, 
which is in continuous and active motion; as long as they remain in the 
vas deferens they are quiescent, but when free to move in the fluid of the 
vesiculse seminales, become very active. 

Origin. The spermatozoa appear at the age of puberty, and are then 
constantly formed until an advanced age. They are developed from the 
nuclei of large, round cells contained in the interior of the seminal 
tubules, as many as fifteen to twenty developing in a single cell. 

When the spermatozoa are introduced into the vagina, they pass readily 
into the uterus and through the Fallopian tubes toward the ovaries, where 
they remain and retain their vitality for a period of from 8 to io days. 

Fecundation is the union of the spermatozoa with the ovum during its 
passage toward the uterus, and usually takes place in the Fallopian tube, 
just outside of the womb. After floating around the ovum in an active 
manner, they penetrate the vitelline membrane, pass into the interior of the 
vitellus, where they lose their vitality, and along with the germinal vesicle 
entirely disappear. 

DEVELOPMENT OF ACCESSORY STRUCTURES. 

Segmentation of the Vitellus. After the disappearance of the 
spermatozoa and the germinal vesicle there remains a transparent, granular, 
albuminous substance, in the centre of which a new nucleus soon appears; 
this constitutes the parent cell , and is the first stage in the development of 
the new being. 

Following this, the vitellus undergoes segmentation; a constriction 
appears on the opposite sides of the vitellus, which gradually deepens, 
until the yelk is divided into two segments, each of which has a distinct 
nucleus and nucleolus; these two segments undergo a further division into 
four, the four into eight, the eight into sixteen, and so on, until the entire 


DEVELOPMENT OF ACCESSORY STRUCTURES. 149 

vitellus is divided into a great number of cells, each of which contains a 
nucleus and nucleolus. 

The peripheral cells of this “mulberry mass” then arrange themselves 
so as to form a membrane, and as they are subjected to mutual pressure, 
assume a polyhedral shape, which gives to the membrane a mosaic appear¬ 
ance. The central part of the vitellus becomes filled with a clear fluid. 
A secondary membrane shortly appears within the first, and the two to¬ 
gether constitute the external and internal blastodermic membranes. 

Germinal Area. At about this period there is an accumulation of 
cells at a certain spot upon the surface of the blastodermic membranes, 
which marks the position of the future embryo. This spot, at first circular, 
soon becomes elongated, and forms the primitive trace , around which is a 
clear space, the area pellucida , which is itself surrounded by a darker 
region, the area opaca. 

The primitive trace soon disappears, and the area pellucida becomes 
guitar-shaped; a new groove, the medullary groove , is now formed, which 
develops from before backward, and becomes the neural canal. 

Blastodermic Membranes. The embryo, at this period, consists of 
three layers, viz.: the external and internal blastodermic membranes, and 
a middle membrane formed by a genesis of cells from their internal sur¬ 
faces. These layers are known as the epiblast, mesoblast and hypoblast. 

The Epiblast gives rise to the central nervous system, the epidermis of 
the skin and its appendages, and the primitive kidneys. 

The Mesoblast gives rise to the dermis, muscles, bones, nerves, blood 
vessels, sympathetic nervous system, connective tissue, the urinary and 
reproductive apparatus and the walls of the alimentary canal. 

The Hypoblast gives rise to the epithelial lining of the alimentary canal 
and its glandular appendages, the liver and pancreas, and the epithelium 
of the respiratory tract. 

Dorsal Laminae. As development advances, the true medullary groove 
deepens, and there arise two longitudinal elevations of the epiblast, the 
dorsal lamince , one on either side of the groove, which grow up, arch 
over and unite so as to form a closed tube, the primitive central nervous 
system. 

The Chorda Dorsalis is a cylindrical rod running almost throughout 
the entire length of the embryo. It is formed by an aggregation of meso- 
blastic cells, and situated immediately beneath the medullary groove. 

Primitive Vertebrae. On either side of the neural canal the cells 
of the mesoblast undergo a longitudinal thickening, which develops and 



160 


HUMAN PHYSIOLOGY. 


extends around the neural canal and the chorda dorsalis, and forms the 
arches and bodies of the vertebrae. They become divided transversely 
into four-sided segments. 

The Mesoblast now separates into two layers; the external, joining with 
the epiblast, forms the somatopleure; the internal, joining with the hypo¬ 
blast, forms the splanchnopleure ; the space between them constituting the 
pleuro-peritoneal cavity. 

Visceral Laminae. The walls of the pleuro-peritoneal cavity are 
formed by a downward prolongation of the somatopleure (the visceral 
lamince), which, as they extend around in front, pinch off a portion of the 
yelk sac (formed by the splanchnopleure), which becomes the primitive 
alimentary canal; the lower portion, remaining outside of the body cavity, 
forms the umbilical vesicle , which after a time disappears. 

Formation of Fcetal Membranes. The Amnion appears shortly 
after the embryo begins to develop, and is formed by folds of the epiblast 
and external layer of the mesoblast, rising up in front and behind, and on 
each side; these amniotic folds gradually extend over the back of the 
embryo to a certain point, where they coalesce, and enclose a cavity, the 
amniotic cavity. The membranous partition between the folds disappears, 
and the outer layer recedes and becomes blended with the vitelline mem¬ 
brane, constituting the chorion , the external covering of the embryo. 

The Allantois. As the amnion develops, there grows out from the 
posterior portion of the alimentary canal a pouch, or diverticulum, the 
allantois, which carries blood vessels derived from the intestinal circula¬ 
tion. As it gradually enlarges, it becomes more vascular, and inserts 
itself between the two layers of the amnion, coming into intimate contact 
with the external layer. Finally, from increased growth, it completely 
surrounds the embryo, and its edges become fused together. 

In the bird, the allantois is a respiratory organ, absorbing oxygen and 
exhaling carbonic acid; it also absorbs nutritious matter from the interior 
of the egg. 

Amniotic fluid. The amnion, when first formed, is in close contact 
with the surface of the ovum ; but it soon enlarges, and becomes filled 
with a clear, transparent fluid, containing albumen, glucose, fatty matters, 
urea and inorganic salts. It increases in amount up to the latter period of 
gestation, when it amounts to about two pints. In the space between the 
amnion and allantois is a gelatinous material, which is encroached upon, 
and finally disappears as the amnion and allantois come in contact, at 
about the fifth month. 


DEVELOPMENT OF ACCESSORY STRUCTURES. 


151 


The Chorion, the external investment of the embryo, is formed by a 
fusion of the original vitelline membrane, the external layer of the amnion, 
and the allantois. The external surface now becomes covered with villous 
processes, which increase in number and size by the continual budding 
and growth of club-shaped processes from the main stem, and give to the 
chorion a shaggy appearance. They consist of a homogeneous granular 
matter, and are penetrated by branches of the blood vessels derived from 
the aorta. 

The presence of villous processes in the uterine cavity is proof positive 
of the previous existence of a foetus. They are characteristic of the 
chorion, and are found under no other circumstances. 

At about the end of the second month the villosities begin to atrophy 
and disappear from the surface of the chorion, with the exception of those 
situated at the points of entrance of the foetal blood vessels, which occupy 
about one-third of its surface, where they continue to grow longer, become 
more vascular, and ultimately assist in the formation of the placenta; the 
remaining two-thirds of the surface loses its villi and blood vessels, and 
becomes a simple membrane. 

The Umbilical Cord connects the foetus with that portion of the 
chorion which forms the foetal side of the placenta. It is a process of the 
allantois, and contains two arteries and a vein, which have a more or less 
spiral direction. It appears at the end of the first month, and gradually 
increases in length, until at the end of gestation it measures about 20 
inches. The cord is also surrounded by a process of the amnion. 

Development of the Decidual Membrane. The interior of the 
uterus is lined by a thin, delicate mucous membrane, in which are im¬ 
bedded immense numbers of tubules, terminating in blind extremities, the 
uterine tubules. At each period of menstruation the mucous membrane 
becomes thickened and vascular, which condition, however, disappears 
after the usual menstrual discharge. When the ovum becomes fecundated, 
the mucous membrane takes on an increased growth, becomes more hyper¬ 
trophied and vascular, sends up little processes, or elevations from its sur¬ 
face, and constitutes the decidua vera. 

As the ovum passes from the Fallopian tube into the interior of the 
uterus, the primitive vitelline membrane, covered with villosities, becomes 
entangled with the processes of the mucous membrane. A portion of the 
decidua vera then grows up on all sides, and encloses the ovum, forming 
the decidua reflexa, while the villous processes of the chorion insert them¬ 
selves into the uterine tubules, and in the mucous membrane between 
them. 


152 


HUMAN PHYSIOLOGY. 


As development advances the decidua reflexa increases in size, and at 
about the end of the fourth month comes in contact with the decidua vera, 
with which it is ultimately fused. 

The Placenta. Of all the embryonic structures, the placenta is the 
most important. It begins to be formed toward the end of the second 
month, and then increases in size until the end of gestation, when it assumes 
an oval or rounded shape, and measures from 7 to 9 inches in length, 6 to 8 
inches in breadth, and weighs from 15 to 20 ounces. It is most frequently 
situated at the upper and posterior part of the inner surface of the uterus. 

The placenta consists of two portions, a foetal and a maternal. 

The Foetal portion is formed by the villi of the chorion, which, by devel¬ 
oping, rapidly increase in size and number. They become branched and 
penetrate the uterine tubules, which enlarge and receive their many rami¬ 
fications. The capillary blood vessels in the interior of the villi also en¬ 
large and freely anastomose with each other. 

The Maternal portion is formed from that part of the hypertrophied and 
vascular decidual membrane between the ovum and the uterus, the decidua 
serotina. As the placenta increases in size, the maternal blood vessels 
around the tubules become more and more numerous, and gradually fuse 
together, forming great lakes, which constitute sinuses in the walls of the 
uterus. 

As the latter period of gestation approaches, the villi extend deeper into 
the decidua, while the sinuses in the maternal portion become larger and 
extend further into the chorion. Finally, from excessive development of 
the blood vessels, the structures between them disappear, and as their walls 
come in contact, they fuse together, so that, ultimately, the maternal and 
festal blood are only separated by a thin layer of a homogeneous substance. 
When fully formed, the placenta consists principally of blood vessels inter¬ 
lacing in every direction. The blood of the mother passes from the ute¬ 
rine vessels into the lakes surrounding the villi; the blood from the child 
flows from the umbilical arteries into the interior of the villi; but there is 
not at any time an intermingling of blood, the two being separated by a 
delicate membrane formed by a fusion of the walls of the blood vessels 
and the walls of the villi and uterine sinuses. 

The function of the placenta is that of a respiratory organ, permitting 
the oxygen of the maternal blood to pass by osmosis through the delicate 
placental membrane into the blood of the foetus; at the same time permit¬ 
ting the carbonic acid and other waste products, the result of nutritive 
changes in the foetus, to pass into the maternal blood, and so to be carried 
to the various eliminating organs. 


DEVELOPMENT OF THE EMBRYO. 


153 


Through the placenta also passes all the nutritious materials of the 
maternal blood which are essential for the development of the embryo. 

At about the middle of gestation there develops beneath the decidual 
membrane a new mucous membrane, destined to perform the functions of 
the old when it is extruded from the womb, along with the other embryonic 
structures, during parturition. 


DEVELOPMENT OF THE EMBRYO. 

Nervous System. The cerebro-spinal axis is formed within the me¬ 
dullary canal by the development of cells from its inner surfaces, which 
as they increase fill up the canal, and there remains only the central canal 
of the cord. The external surface gives rise to the dura mater and pia 
mater. The neural canal thus formed is a tubular membrane; it termi¬ 
nates posteriorly in an oval dilatation, and anteriorly in a bulbous extremity, 
which soon becomes partially contracted, and forms the anterior, middle 
and posterior cerebral vesicles, from which are ultimately developed the 
cerebrum, the corpora quadrigemina, and medulla oblongata, respectively. 

The anterior vesicle soon subdivides into two secondary vesicles, the 
larger of which becomes the hemispheres, the smaller, the optic thalami; 
the posterior vesicle also divides into two; the anterior becoming the 
cerebellum, the posterior, the pons Varolii and medulla oblongata. 

About the seventh week the straight chain of cerebral vesicles becomes 
curved from behind forward and forms three prominent angles. As devel¬ 
opment advances, the relative size of the encephalic masses changes. The 
cerebrum developing more rapidly than the posterior portion of the brain, 
soon grows backward and arches over the optic thalami and the tubercula 
quadrigemina; the cerebellum overlaps the medulla oblongata. 

The surface of the cerebral hemispheres is at first smooth, but at about the 
fourth month begins to be marked by the future fissures and convolutions. 

The Eye is formed from a little bud projecting from the side of the 
anterior vesicle. It is at first hollow, but becomes lined with nervous 
matter, forming the optic nerve and retina ; the remainder of the cavity is 
occupied by the vitreous body. The anterior portion of the pouch becomes 
invaginated and receives the crystalline lens y which is a product of the 
epiblast, as is also the cornea. The iris appears as a circular membrane 
without a central aperture, about the seventh week; the eyelids are formed 
between the second and third months. 

The Internal Ear is developed from the auditory vesicle , budding 
from the third cerebral vesicle; the membranous vestibule appears first, 


K 


154 


HUMAN PHYSIOLOGY. 


and from it diverticula are given off, which become the semi-circular 
canals and cochlea. 

The cavity of the tympanum, the Eustachian tube, and the external 
auditory canal are the remains of the first branchial cleft; the cavity of this 
cleft being subdivided into the tympanum and external auditory meatus by 
the membrana tympani. 

The Skeleton. The. chorda dorsalis, the primitive part of the verte¬ 
bral column, is a cartilaginous rod situated beneath the medullary groove. 
It is a temporary structure, and disappears as the true bony vertebrae 
develop. On either side are the quadrate masses of the mesoblast, the 
primitive vertebrae, which send processes upward and around the medul¬ 
lary groove, and downward and around the chorda dorsalis, forming in 
these situations the arches and bodies of the future vertebrae. 

More externally the outer layer of the mesoblast and epiblast arch 
downward and forward, forming the ventral laminae, in which develop 
the muscles and bones of the abdominal walls. 

The true cranium is an anterior development of the vertebral column, 
and consists of the occipital, parietal and frontal segments, which corres¬ 
pond to the three cerebral vesicles. The base of the cranium consists, at 
this period, of a cartilaginous rod on either side of the anterior extremity 
of the chorda dorsalis, in which three centres of ossification appear, the 
basi-occipital, the basi-sphenoidal, and the pre-sphenoidal. They ultimately 
develop into the basilar process of the occipital bone and the body of the 
sphenoid. 

The entire skeleton is at first either membranous or cartilaginous. At 
the beginning of the second month centres of ossification appear in the 
jaws and clavicle; as development advances, the ossific points in all the 
future bones extend, until ossification is completed. 

The limbs develop from four little buds projecting from the sides of the 
embryo, which, as they increase in length, separate into the thigh, leg and 
foot, and the arm, forearm and hand; the extremities of the limbs undergo 
subdivision, to form the fingers and toes. 

Face and Visceral Arches. In the facial and cervical regions the 
visceral laminae send up three processes, the visceral arches , separated by 
clefts, the visceral clefts. 

The first , or the mandibular arches , unite in the median line to form 
the lower jaw, and superiorly form the malleus. A process jutting from 
its base grows forward, unites with the fronto-nasal process growing from 
above, and forms the upper jaw. When the superior maxillary processes 


DEVELOPMENT OF THE EMBRYO. 


155 


fail to unite, there results the cleft-palate deformity; if the integument also 
fails to unite, there results the hare-lip deformity. The space above the 
mandibular arch becomes the mouth. 

The second arch develops the incus and stapes bones, the styloid process 
and ligament, and the lesser cornu of the hyoid bone. The cleft between 
the first and second arches partially closes up, but there remains an open¬ 
ing at the side which becomes the Eustachian tube, tympanic cavity, and 
external auditory meatus. 

The third arch develops the body and greater cornu of the hyoid 
bone. 

Alimentary Canal and its Appendages. The alimentary canal is 
formed by a pinching off of the yelk sac by the visceral plates as they 
grow downward and forward. It consists of three distinct portions, the 
fore gut, the hind gut, and the central part, which communicates for some 
time with the yelk sac. It is at first a straight tube, closed at both 
extremities, lying just beneath the vertebral column. The canal gradu¬ 
ally increases in length, and becomes more or less convoluted; at its 
anterior portion two pouches appear, which become the cardiac and 
pyloric extremities of the stomach. At about the seventh week the 
inferior extremity of the intestine is brought into communication with the 
exterior, by an opening, the anus. Anteriorly the mouth and pharynx are 
formed by an involution of epiblast, which deepens until it communicates 
with the fore gut. 

The Liver appears as a slight protrusion from the sides of the alimen¬ 
tary canal, about the end of the first month; it grows very rapidly, attains 
a large size, and almost fills up the abdominal cavity. The hepatic cells 
are derived from the intestinal epithelium, the vessels and connective 
tissue from the mesoblast. 

The Pancreas is formed by the hypoblastic membrane. It originates 
in two small ducts budding from the duodenum, which divide and subdi¬ 
vide, and develop the glandular structure. 

The Lungs are developed from the anterior part of the oesophagus. At 
first a small bud appears, which, as it lengthens, divides into two branches; 
secondary and tertiary processes are given off these, which form the bron¬ 
chial tubes and air cells. The lungs originally extended into the abdomi¬ 
nal cavity, but became confined to the thorax by the development of the 
diaphragm. 

The Bladder is formed by a dilatation of that portion of the allantois 
remaining within the abdominal cavity. It is at first pear-shaped, and 
communicates with the intestine, but later becomes separated, and opens 


156 


HUMAN PHYSIOLOGY. 


exteriorly by the urethra. It is attached to the abdominal walls by a 
rounded cord, the urachus, the remains of a portion of the allantois. 

Genito-Urinary Apparatus. The Wolffian bodies appear about the 
thirtieth day, as long hollow tubes running along each side of the primi¬ 
tive vertebral column. They are temporary structures, and are sometimes 
called the primordial kidneys. The Wolffian bodies consist of tubules 
which run transversely and are lined with epithelium; internally they 
become invaginated to receive tufts of blood vessels; externally they open 
into a common excretory duct, the duct of the Wolffian body , which unites 
with the duct of the opposite body, and empties into the intestinal canal 
at a point opposite the allantois. On the outer side of the Wolffian body 
there appears another duct, the duct of Muller, which also opens into the 
intestine. 

Behind the Wolffian bodies are developed the structures which become 
either the ovaries or testicles. In the development of the female, the 
Wolffian bodies and their ducts disappear; the extremities of the Mullerian 
ducts dilate and form the fimbriated extremity of the Fallopian tubes, while 
the lower portions coalesce to form the body of the uterus and vagina, 
which now separate themselves from the intestine. 

In the development of the male, the Mullerian ducts atrophy, and 
the ducts of the Wolffian body ultimately form the epididymis and vas 
deferens. About the seventh month the testicles begin to descend, 
and by the ninth month have passed through the abdominal ring into 
the scrotum. 

The Kidneys are developed out of the Wolffian bodies. They consist of 
little pyramidal lobules, composed of tubules which open at the apex into 
the pelvis. As they pass outward they become convoluted and cup-shaped 
at their extremities, receive a tuft of blood vessels, and form the Mal¬ 
pighian bodies. 

The ureters are developed from the kidneys, and pass downward to be 
connected with the bladder. 

The Circulatory Apparatus assumes three different forms at different 
periods of life, all having reference to the manner in which the embryo 
receives nutritious matter and is freed of waste products. 

The Vitelline circulation appears first and absorbs nutritious material 
from the vitellus. It is formed by blood vessels which emerge from the 
body and ramify over a portion of the vitelline membrane, constituting the 
area vasculosa. The heart, lying in the median line, gives off two arches 
which unite to form the abdominal aorta, from which two large arteries 
are given off, passing into the vascular area; the venous blood is returned 


DEVELOPMENT OF THE EMBRYO. 


157 


by veins which enter the heart. These vessels are known as the omphalo¬ 
mesenteric arteries and veins. The vitelline circulation is of short dura¬ 
tion in the mammals, as the supply of nutritious matter in the vitellus soon 
becorties exhausted. 

The Placental circulation becomes established when the blood vessels 
in the allantois enter the villous processes of the chorion and come into 
close relationship with the maternal blood vessels. This circulation lasts 
during the whole of intra-uterine life, but gives way at birth to the adult 
circulation, the change being made possible by the development of the 
circulatory apparatus. 

The Heart appears as a mass of cells coming off from the anterior por¬ 
tion of the intestine; its central part liquefies, and pulsations soon begin. 
The heart is at first tubular, receiving posteriorly the venous trunks and 
giving off anteriorly the arterial trunks. It soon becomes twisted upon 
itself, so that the two extremities lie upon the same plane. 

The heart now consists of a single auricle and a single ventricle. A 
septum growing from the apex of the ventricle divides it into two cavities, 
a right and a left. The auricles also become partly separated by a septum 
which is perforated by the foramen ovale. The arterial trunk becomes 
separated by a partition, into two canals, which become, ultimately, the 
aorta and pulmonary artery. The auricles are separated from the ventri¬ 
cles by incomplete septa, through which the blood passes into the ventricles. 

Arteries. The aorta arises from the cephalic extremity of the heart and 
divides into two branches which ascend, one or. each side of the intestine, 
and unite posteriorly to form the main aorta; posteriorly to these first 
aortic arches four others are developed, so that there are five altogether 
running along the visceral arches. The two anterior soon disappear. The 
third arch becomes the internal carotid and the external carotid; a part 
of the fourth arch , on the right side, becomes the subclavian artery, and 
the remainder atrophies and disappears, but on the left side it enlarges 
and becomes the permanent aorta; the fifth arch becomes the pulmonary 
artery on the left side. The communication between the pulmonary artery 
and the aorta, the ductus arteriosus , disappears at an early period. 

Veins. The venous system appears first as two short, transverse veins, 
the canals of Cuvier, formed by the union of the vertebral veins and the 
cardinal veins, which empty into the auricle. The inferior vena cava is 
formed as the kidneys develop, by the union of the renal veins, which, in 
a short time, receive branches from the lower extremities. The sub¬ 
clavian veins join the jugular as the upper extremities develop. The heart 
descends in the thorax, and the canals of Cuvier become oblique; they 


158 


HUMAN PHYSIOLOGY. 


shortly communicate by a transverse duct, which ultimately becomes the 
left innominate vein. The left canal of Cuvier atrophies and becomes a 
fibrous cord. A transverse branch now appears, which carries the blood 
from the left cardinal vein into, the right, and becomes the vena a2ygos 
minor; the right cardinal vein becomes the vena azygos major. 

Circulation of Blood in the Foetus. The blood returning from the 
placenta, after having received oxygen, and being freed from carbonic acid, 
is carried by the umbilical vein to the under surface of the liver; here a 
portion of it passes through the ductus venosus into the ascending vena 
cava, while the remainder flows through the liver, and passes into the vena 
cava by the hepatic veins. When the blood is emptied into the right 
auricle, it is directed by the Eustachian valve, through the foramen ovale, 
into the left auricle, thence into the left ventricle, and so into the aorta to 
all parts of the system. The venous blood returning from the head and 
upper extremities is emptied, by the superior vena cava, into the right 
auricle, from which it passes into the right ventricle, and thence into the- 
pulmonary artery. Owing to the condition of the lung, only a small por¬ 
tion flows through the pulmonary capillaries, the greater part passing 
through the ductus arteriosus, which opens into the aorta at a point below 
the origin of the carotid and subclavian arteries. The mixed blood now 
passes down the aorta to supply the lower extremities, but a portion of 
it is directed, by the hypogastric arteries, to the placenta, to be again 
oxygenated. 

At birth, the placental circulation gives way to the circulation of the 
adult. As soon as the child begins to breathe, the lungs expand, blood 
flows freely through the pulmonary capillaries, and the ductus arteriosus 
begins to contract. The foramen ovale closes about the tenth day. The 
unbilical vein, the ductus venosus, and the hypogastric arteries become 
impervious in several days, and ultimately form rounded cords. 


TABLE OF PHYSIOLOGICAL CONSTANTS. 


15 » 


TABLE OF PHYSIOLOGICAL CONSTANTS. 


Mean height of male, 5 feet 6^ inches; of female, 5 feet 2 inches. 
Mean weight of male, 145 pounds; of female, 121 pounds. 

Number of chemical elements in the human body; from 16 to 18. 
Number of proximate principles in the human body; about 100. 
Amount of water in the body weighing 145 pounds; 108 pounds. 
Amount of solids in the body weighing 145 pounds; 36 pounds. 

Amount of food required daily; 16 ounces meat, 19 ounces of bread, 3^ 
ounces of fat, 52 ounces of water. 

Amount of saliva secreted in 24 hours ; about 3j£ pounds. 

Function of saliva; converts starch into glucose. 

Active principle of saliva; ptyalin. 

Amount of gastric juice secreted in 24 hours; from 8 to 14 pounds. 
Functions of gastric juice ; converts albumen into albuminose. 
Active principles of gastric juice ; pepsin and hydrochloric acid. 
Duration of digestion; from 3 to 5 hours. 

Amount of intestinal juice secreted in 24 hours; about 1 pound. 

Function of intestinal juice ; converts starch into glucose. 

Amount of pancreatic juice secreted in 24 hours; about 1^ pounds. 
Active principles of pancreatic juice; pancreatin and trypsin. 



Amount of bile poured into the intestines daily; about 2^ pounds. 


f 1 . Assists in the emulsification of fats. 

I 2. Stimulates the peristaltic movements, 
j 3. Prevents putrefactive changes in the food. 
I 4. Promotes the absorption of the fat. 


Functions: 


Amount of blood in the body; from 16 to 18 pounds. 

Size of red corpuscles; °f an inch* 

Size of white corpuscles ; °f an inch. 

Shape of red corpuscles ; circular biconcave disks. 

Shape of white corpuscles ; globular. 

Number of red corpuscles in a cubic millimetre of blood (the cubic 
of an inch); 5,000,000. 



160 


HUMAN THYSIOLOGY. 


Function of red corpuscles ; to carry oxygen from the lungs to the tissues. 

Frequency of the heart’s pulsations per minute; 72, on the average. 

Velocity of the blood movement in the arteries; about 16 inches per 
second. 

Length of time required for the blood to make an entire circuit of the 
vascular system ; about 20 seconds. 

Amount of air passing in and out of the lungs at each respiratory act; 
from 20 to 30 cubic inches. 

Amount of air that can be taken into the lungs on a forced inspiration; 
no cubic inches. 

Amount of. reserve air in the lungs after an ordinary expiration; 100 
cubic inches. 

Amount of residual air always remaining in the lungs; about 100 cubic 
inches. 

Vital capacity of the lungs ; 230 cubic inches. 

Entire volume of air passing in and out of the lungs in 24 hours; about 
400 cubic feet. 

Composition of the air; nitrogen, 79.19, oxygen, 20.81, per 100 parts. 

Amount of oxygen absorbed in 24 hours; 18 cubic feet. 

Amount of carbonic acid exhaled in 24 hours; 14 cubic feet. 

Temperature of the human body at the surface; 98^° F. 

Amount of urine excreted daily; from 40 to 50 ounces. 

Amount of urea excreted daily; 512 grains. 

Specific gravity of urine; from 1.010 to 1.015. 

Number of spinal nerves ; 31 pairs. 

Number of roots of origin; two; 1st, anterior, motor; 2d, posterior, 
sensory. 

Rate of transmission of nerve force; about 100 feet per second. 

Number of cranial nerves; 12 pairs. 


' 1. Olfactory, or 1st pair. 

2. Optic, or 2d pair. 

3. Auditory, or 8th pair. 

4. Chorda tympani for anterior of tongue. 

5. Branches of glosso-pharyngeal, 01 ;h pair, 


Nerves of special sense : - 



for posterior ^ of tongue. 


Motor nerves to eyeball and accessory structures ; motor oculi, or 3d 
pair; pathetic, or 4th pair; abducens, or 6th pair. 

Motor nerves to facial muscles; portio dura, facial, or 7th pair. 

Motor nerve to tongue ; hypoglossal or 12th pair. 

Motor nerve to laryngeal muscles; spinal accessory or nth pair. 




TABLE OF PHYSIOLOGICAL CONSTANTS. 


161 


Sensory nerve of the face; trifacial or 5th pair. 

Sensory nerve of the pharynx ; glosso-pharyngeal or 9th pair. 

Sensory nerve of the lungs, stomach, etc.; pneumogastric or 10th pair. 

Length of spinal cord ; 16 to 18 inches, weight i ]/ 2 ounces. 

Point of decussation of motor fibres ; at the medulla oblongata. 

Point of decussation of sensory fibres ; throughout the spinal cord. 

Function of antero-lateral columns of spinal cord; transmit motor 
impulses from the brain to the muscles. 

Functions of the posterior columns; assist in the coordination of mus¬ 
cular movements. 

Functions of the medulla oblongata; controls the functions of insaliva¬ 
tion, mastication, deglutition, respiration, circulation, etc. 

Functions of the corpora quadrigemina; physical centres for sight. 

Functions of the corpora striata; centres for motion. 

Functions of the optic thalami; centres for sensation. 

Function of the cerebellum ; centre for the coordination of muscular 
movements. 

Function of the cerebrum ; centre for intelligence, reason and will. 

Centre for articulate language; 3d frontal convolution on left side of 
cerebrum. 

Number of coats to the eye; three; 1st, cornea and sclerotic; 2d, choroid ; 
3d, retina. 

Function of iris; regulates the amount of light entering the eye. 

Function of crystalline lens; refracts the rays of light so as to form an 
image on the retina. 

Function of retina; receives the impressions of light. 

Function of membrana tympani; receives and transmits waves of sound 
to internal ear. 

Function of Eustachian tube; regulates the passage of air into and from 
the middle ear. 

Function of semi-circular canals; assist in maintaining the equipoise 
of the body. 

Function of the cochlea; appreciates the shades and combinations of 
musical tones. 

Size of human ovum ; of an inch in diameter. 

Size of spermatozoa; of an inch in length. 

Function of the placenta; acts as a respiratory and digestive organ for 
the foelus. 

Duration of pregnancy; 280 days. 



TABLE SHOWING RELATION OF WEIGHTS AND 
MEASURES OF THE METRIC SYSTEM TO APPROX¬ 
IMATE WEIGHTS AND MEASURES OF THE U. S. 


One Myriametre 
One Kilometre 
One Hectometre 
One Decametre 

One Metre 

One Decimetre 
One Centimetre 

One Millimetre 


MEASURES OF LENGTH. 


= 10,000 metres 
= i ,000 “ 


{ 

{ 


100 “ 

10 “ 

the ten millionth part of a 'j 
quarter of thp Meridian of > 

the Earth |WUJ4 - J 

the tenth part of one metre 
the one hundredth part of) 
one metre j 

the one thousandth part of 1 
one metre J 


= 32800. feet, 
= 3280. “ 

= 328.0 « 

= 32.80 “ 


= 39.368 inches. 


= 3.936 

= -393 (f) “ 

■° 39 (A) “ 


One Myriagramme- 
One Kilogramme - 
One Hectogramme; 
One Decagramme : 

One Gramme = 

One Decigramme = 

One Centigramme ; 

One Milligramme = 


WEIGHTS. 

: 10,000 grammes 
1,000 “ 

100 “ 

10 “ 

J the weight of a cubic centi- 
( metre of water at 4 0 C. 

: the tenth part of one gramme 
f the hundredth part of one 
‘ \ gramme 

f the thousandth part of one 
\ gramme 


26^ pounds Troy. 
2 % “ 

31^ ounces “ 

2 y z drachms “ 

15-434 grains. 

1-543 (iK) “ 

•154 ( l A) “ 


}= 

e = 

}= 

} = - OI 5 (s\) 


One Myrialitre 
One Kilolitre 
One Hectolitre 

One Decalitre 

One Litre 

One Decilitre 

One Centilitre 

One Millilitre 


MEASURES OF CAPACITY. 


{ 


10 cubic Metres or the 
measui-e of 10 Milliers of 
water 

1 cubic Metre or the meas¬ 
ure of 1 Millier of water 
100 cubic Decimetres or 
the measure of 1 Quintal 
of water 

10 cubic Decimetres or the 
measure of 1 Myriagramme 
of water 

1 cubic Decimetre or the 
measure of 1 Kilogramme 
of water 

100 cubic Centimetres or 
the measure of 1 Hecto¬ 
gramme of water 
10 cubic Centimetres or 
the measure of one Deca¬ 
gramme of water 
1 cubic Centimetre or the 
measure of 1 gramme of 
water 1 


} 


= 2600. gallons. 
= 260. “ 

= 26. “ 


2.6 


2.1 pints. 


3.3 ounces. 


2.7 drachms. 


— 16.2 minims. 



INDEX 


PAGE 


A BDUCENS NERVE. 90 

Aberration, chromatic. 135 

-spherical. 135 

Absorption. 33 

-by the lacteals. 38 

-by the blood vessels. 34 

-of oxygen in respiration. 56 

Accommodation of the eye. 135 

Adipose tissue, uses of in the body. 12 

Adult circulation, establishment of at 

birth. 157 

Air, atmospheric, composition of. 56 

-amount exchanged in respira¬ 
tion .. 56 

-changes in during respiration... 57 

Albumen, uses of in the body. 13 

Albuminoid substances. 13 

Alcohol, action of.. 21 

Alimentary principles, classification of 19 

-albuminous principles. 19 

-saccharine principles. 19 

-oleaginous principles. 19 

-inorganic principles. 20 

Alimentary canal, development of.. 155 

Allantois, development and function of 150 

Amnion, formation of. 150 

Animal heat. 58 

Anterior columns of spinal cord. 105 

Area, germinal. 149 

Arteries, properties of. 49 

Asphyxia.. 58 

Astigmatism. 135 

Axis, cerebro-spinal. 100 

-cylinder of nerves. 81 


TDILE. 

Bladder, urinary. 

Blastodermic membranes. 

Blood... 


-composition of plasma. 

-coagulation of.. 

-coloring matter of. 

-changes in, during respiration. 

-circulation of. 

-rapidity of flow in arteries. 

-rapidity of flow in capillaries... 

-pathological conditions of.. 

-corpuscles. 

-origin of. 

- pressure . 

Burdach, column of. 


75 

69 

148 

39 

40 

43 

34 

56 

40 
55 
5i 
45 

41 

42 

49 

102 


PAGE 


r'ANALS OF CUVIER . 157 

Capillary blood vessels. 50 

Capsule, internal. 115 

-external. 115 

Caudate nucleus. 115 

Cells, structure of. 16 

-manifestations of life by. 16 

-ofanterior horns of gray matter. 104 

Centre for articulate language. 121 

Cerebrum. 118 

-fissures and convolutions. 188 

-functions of. 120 

-localization of functions. 121 

-motor area of. 122 

-special centres of. 122 

Cerebellum. ri6 

-forced movements of. 117 

Cerebral vesicles of embryo . 153 

Chemical composition of human body. 10 

- elements, proximate quantity 

of in body. 15 

Chorda dorsalis. 149 

-tympani nerve, course and func¬ 
tion of. 93 

Chorion. 151 

Chyle. 38 

Ciliary muscle. 131 

Circulation of blood. 45 

Claustrumv. 115 

Cochlea. 139 

Columns of spinal cord. 101 

Corium. 85 

Corpora Wolffiana. 156 

-quadrigemina. 114 

Corpus luteum. 145 

-striatum. 114 

Corti, organ of.. 140 

Cranial nerves. 87 

Crura cerebri. 113 

Crystalline lens. 132 


-r\ECIDUAL MEMBRANE. 151 

Decussation of motor and sen¬ 
sory fibres . 104 

Deglutition. 26 

-nervous circle of.. hi 

Development of accessory structures 

of embryo. 148 

Digestion. 23 

Ductus arteriosus. 158 

-venosus. 158 


163 


venosus 






























































































































164 


INDEX. 


PAGE 

PTAR. 136 

Electrotonus. 86 

Embryo, development of. 153 

Endolymph. 139 

Epidermis. 85 

Epididymis. 147 

Epiglottis. 27 

Eustachian tube. 138 

Excretion. 66 

Eye. 130 

-refracting apparatus of.. 133 

-blind spot of... 134 


PACIAL NERVE. 92 

-paralysis, symptoms of... 93 

Fallopian tubes. 144 

Faeces. 33 

Fat, uses of in the body. 13 

Female organs of generation. 144 

Fissures and convolutions of brain. 118 

Food. 18 

-percentage composition of. 22 

-daily amount required. 22 

-albuminous principles of.. 20 

-saccharine principles of.. 20 

-oleaginous principles of.. 20 

-inorganic principles of.. 19 

Fovea centralis... 134 


C' ALVANIC CURRENTS, EF- 

Ganglia. 

-ophthalmic. 

-Gasserian... 

-spheno-palatine. 

-otic. 

-sub-maxillary. 

-semi-lunar. 

Gases of the intestine. 

-condition of, in blood. 

Gastric juice. 

-action of.... 

Generation, male organs of. 

-female organs of.. 

Globules of the blood. 

-of the lymph. 

Glomeruli of the kidneys. 

Glosso-pharyngeal nerve. 

Glottis, respiratory movements of. 

Glycogen. 

Glycogenic function of liver. 

Goll, column of.. 

Graafian follicles... 

Gray matter of nervous system. 


86 

80 

123 

9 i 

122 

123 

123 

124 

35 
57 

28 

29 

*47 

144 

4i 

36 
69 
95 
54 
76 

75 

102 

144 

80 


H AIR .;••• 

A Haemoglobin. 
Hearing, sense of... 
Heart. 


— valves of.. 

— sounds of. 

— influence of pneumogastric 

nerve upon. 

— ganglia of.. 

— force exerted by left ventricle... 


77 

42 

136 

45 

45 

46 

48 

48 

47 


PAGE 


Heart, woik done by. 47 

-course of blood through. 46 

-influence of nervous system 

upon. 48 

Hyaloid membrane. 132 

Hypermetropia. 135 

Hypoglossal nerve... 99 


TNCUS BONE. 137 

Ingesta and egesta, comparison of 

in 24 hours. 22 

Insalivation. 24 

-nervous circle of.. 25 

Inspiration, movements of thorax in... 54 

Internal capsule. 115 

-results of injury to. 115 

Intestinal juice. 30 

Iris. 130 

-action of.. 134 

Island of Reil. 119 

T7TDNEYS. 66 

-excretion of urine by. 70 

T ABYRINTH OF INTERNAL 

ear. 138 

-function of cochlea. 140 

-function of semicircular canals. 140 

Language, articulate, centre for. 121 

Larynx. 52 

Lateral columns of spinal cord. 101 

Laws of muscular contraction. 87 

Laxator tympani muscle. 138 

Lens, crystalline. 132 

Lime phosphate. 12 

Liver. 73 

-secretion of bile by. 75 

-glycogenic function of. 75 

-elaboration of blood. 75 

-cells. 74 

Localization of functions in cerebrum. 121 

Lungs. 53 

-changes in blood while passing 

through. 57 

Lymph. 36 

Lymphatic glands. 36 

-vessels, origin and course of... 35 


TWFAMMARY GLANDS. 

Malleus bone. 

Mastication. 

-nervous circle of.. 

•-muscles of. 

Medulla oblongata. 

-properties and functions of. 

Membrana basilaris. 

- tympani. 

Menstruation.. 

Middle ear. 

Milk. 

Motor centres of cerebrum. 

Muscles, properties of.. 

Myopia. 


63 

x 37 

2 3 

2 3 

2 4 
109 
no 
140 
*37 
145 
137 

63 

122 

85 

*35 



























































































































































INDEX. 


165 


TSJERVE, OLFACTORY. 

x ^ --optic. 


motor oculi. 


facial. 


spinal accessory. 


force. 


sory. 


QLFACTORY 

Ophthalmic g 
Optic nerves. 


NERVES. 


>ACINIAN CORPUSCLES. 


Perspiration. 


Pressure of blood in arteries. 


PAGE 


88 


88 


89 


90 


90 


90 


92 


94 


95 


95 


98 


99 


80 


83 


87 

nd 


82 


84 


87 

:n- 


104 


III 


84 


84 


80 


80 


80 


123 


115 


115 


88 


123 


88 


xx 5 


Ix 5 


140 


123 


144 


144 


x 45 

nn 

42 


83 


3 ° 


90 


29 


1.39 


69 


93 


142 


9 

... 

152 


95 


112 


34 


105 


105 


23 


135 


49 


II 


II 


12 


x 3 


15 


PAGE 


Proximate quantity of chemical ele¬ 
ments in body. 15 

Ptyalin. 25 

Pulse. 49 

Pyramidal tracts. 101 

DED CORPUSCLES OF 

^ blood . 41 

Reflex movements of spinal cord. ic6 

-action, laws of.. 107 

Reproduction. 144 

Respiration. 52 

-movements of.. 54 

-nervous mechanism of. 55 

-types of.. 55 

-nervous circle of.. 112 

Retina. 134 

OALIVA . 25 

^ Sebaceous glands. 78 

Secretion. 60 

Semi-circular canals. 139 

Semen. 148 

Sight, sense of.. 130 

Skin. 76 

-relative sensibility of.. 126 

-appendages of.. 77 

Smell, sense of... 129 

Sounds of heart. 46 

Spermatozoa. 148 

Spheno-palatine ganglion. 122 

Spinal accessory nerve. 98 

Spinal cord. 101 

-membranes of. 100 

-structure of white matter. 101 

-structure of gray matter. 102 

-properties of... 104 

-function of as a conductor. 105 

-as an independent centre. 106 

-decussation of motor and sen¬ 
sory fibres. 104 

-reflex action of.. 106 

-special centres of.. 106 

-paralysis, from disease of.. 108 

-nerves, origin of.. 102 

-course of anterior and posterior 

roots of.. 102 

Spleen. 65 

Stapes bone. 137 

Starvation, phenomena of.. 18 

Stomach. 26 

Structural composition of the body... 15 

Submaxillary ganglion. 123 

Sugar, uses of in the body. 12 

Supra-renal capsules. 66 

Sudoriparous glands. 78 

Sympathetic nervous system. 123 

-properties and functions of.. 124 


npASTE, SENSE OF. 

Teeth. 

Tensor tympani muscle. 

Testicles.. 

Thoracic duct. . 

Thorax, enlargement of in inspiration 


127 

128 

23 

x 37 

x 47 


36 


54 













































































































































































166 


INDEX. 


PAGE 


Tissues, classification of.. 17 

Tongue. 127 

-motor nerve of.. 128 

-sensory nerve of. 128 

Touch, sense of.. 126 

Tiirck column... 101 

U MBILICAL CORD . 151 

Urea. 72 

Uric acid. 72 

Urine. 70 

-composition of. 71 

-average quantity of constitu¬ 
ents secreted daily. 71 

Urination, nervous mechanism of.. 70 

Uterus. 145 


XT APOR, WATERY, 
v breath. 

Vascular glands. 

-system, development of.. 

Vaso-motor nerves, origin of.... 

Veins.. 

Vesiculae seminales. 

Vision, psychical centre for.. 

-physical centre for. 

Vital capacity of lungs. 

Vocal cords..... 

Voice. 


PAGE 

O F 


57 


65 

156 

hi 

5 i 


i47 

122 

114 

56 

141 

141 


^yATER, AMOUNT OF IN 

Wolffian bodies. 


11 

156 




















































* - 

m 

L v • 

































■ 





































- 
































- 

































* • 

































- 




















































- - 4 






















































- 

■ 




































































CATALOGUE No. 7. 


FEBRUARY. 1886. 



A CATALOGUE 


Books for Students; 

INCLUDING A FULL LIST OF 

The ? Quiz- Comp ends?, 

' MANUALS, 

Text-Books and Students’ Aids, 

PUBLISHED BY 

P. BLAKISTON, SON & CO. 

Medical Booksellers, Importers and Publishers . 

LARGE STOCK OF ALL STUDENTS’ BOOKS, AT 
THE LOWEST PRICES. 

No. 1012 WALNUT STREET, 

PHILADELPHIA. 


*** For sale by all Booksellers, or any book will be sent by mail, 
postpaid, upon receipt of price. Catalogues of books on all branches 
of Medicine, Dentistry, Pharmacy, etc., supplied upon application. 

































? QUIZ-COMPENDS? 

A NEW SERIES OF COMPENDS FOR STUDENTS 

For Use in the Quiz Class and when 
Preparing for Examinations. 

Price of Each, Bound in Cloth, $1.00 Interleaved, $1.25. 

Based on the most popular text-books, and on the lec¬ 
tures of prominent professors, they form a most complete 
set of manuals, containing information nowhere else 
collected in such a condensed, practical shape. The 
authors have had large experience as quiz masters and 
attaches of colleges, with exceptional opportunities for 
noting' the most recent advances and methods. The 
arrangement of the subjects, illustrations, types, etc., are 
all of the most improved form, and the size of the books 
is such that they may be easily carried in the pocket. 
They are constantly revised, so as to include the latest 
and best teachings, and can be used by students of any 
college. 

No. 1. ANATOMY. (Illustrated.) 

THIRD REVISED EDITION. 

A Compend of Human Anatomy. By Samuel O. L. 
Potter, m.a., m.d., U. S. Army. With 63 Illustrations. 

“ The work is reliable and complete, and just what the student 
needs in reviewing the subject for his examinations .”—The Physi¬ 
cian and Surgeon's Investigator , Buffalo, N. Y. 

“ The arrangement is well calculated to facilitate accurate memo¬ 
rizing, and the illustrations are clear and good .”—North Carolina 
Medical Journal. 

Nos. 2 and 3. PRACTICE. 

NEW REVISED EDITIONS. 

A Compend of the Practice of Medicine, especially 
adapted to the use of Students. By Dan’l E. Hughes, 
m.d., Demonstrator of Clinical Medicine in Jefferson 
Medical College, Philadelphia. Second Edition. En¬ 
larged and thoroughly Revised. In two parts. 

Part I.—Continued, Eruptive, and Periodical Fevers, 
Diseases of the Mouth, Stomach, Intestines, Peritoneum, 
Biliary Passages, Liver, Kidneys, Intestinal Parasites, etc., 
and General Diseases. 

Part II.—Diseases of the Respiratory System, Circu¬ 
latory System and Blood, Nervous System, etc. 

Price of each Book, Cloth, $1.00. Interleaved for Notes, $1.25. 



THE ? QUIZ-COMPENDS ?. 


3 


*** These little books can be regarded as a full set of 
notes upon the Practice of Medicine, containing the 
Synonyms, Definitions, Causes, Symptoms, Prognosis, 
Diagnosis, Treatment, etc., of each disease, and includ¬ 
ing a number of new prescriptions. They have been 
compiled from the lectures of prominent Professors, and 
reference has been made to the latest writings of Pro¬ 
fessors Flint, Da Costa, Bartholow, Roberts, etc. 

“ It is brief and concise, and at the same time possesses an accu¬ 
racy not generally found in compends.”— Jas. M. French, M.D., 
Ass’t to the Prof, of Practice, Medical College of Ohio, Cincinnati. 

“The book seems very concise, yet very comprehensive. . . . 

An unusually superior book.”— Dr. E. T. Bruen, Demonstrator 
of Clinical Medicine, University of Pennsylvania. 

“ I have used it considerably in connection with my branches in 
the Quiz-class of the University of La.”— J. H. Bemiss. 

“ Dr. Hughes has prepared a very useful little book, and I shall 
take pleasure in advising my class to use it.”— Dr. George ]V. 
Hall, Prof, of Practice, St. Louis College of Phys. and Surgeons. 

No. 4. PHYSIOLOGY. Illustrated. 

THIRD REVISED EDITION. 

Compend of Human Physiology, adapted to the use 
of Students. By Albert P. Brubaker, m.d., De¬ 
monstrator of Physiology in Jefferson Medical College, 
Philadelphia. Third Ed. Enlarged and Revised. 

“ Dr. Brubaker deserves the hearty thanks of medical students 
for his Compend of Physiology. He has arranged the fundamental 
and practical principles of the science in a peculiarly inviting and 
accessible manner. I have already introduced the work to my 
class.”— Maurice N. Miller, M.D., Instructor in Histology, for¬ 
merly Demonstrator of Physiology, University City of New York. 

“ ‘ Quiz-Compend ’ No. 4 is fully up to the high standard estab¬ 
lished by its predecessors of the same series.”— Medical Bulletin, 
Ph iladelphia. 

“ I can recommend it as a valuable aid to the student.”— C. N. 
Ellinwood, M.D., Professor of Physiology, Cooper Medical Col¬ 
lege, San Francisco. 

“ This is a well written little book.”— London Lancet. 

No. 5. OBSTETRICS. Second Ed. 

A Compend of Obstetrics. For Physicians and Students. 
By Henry G. Landis, m.d., Professor of Obstetrics 
and Diseases of Women, in Starling Medical College, 
Columbus. New Revised Ed. New Illustrations. 

“ We have no doubt that many students will find in it a most 
valuable aid in preparing for examination.”— The American Jour¬ 
nal of Obstetrics. 

“ It is complete, accurate and scientific. The very best book of 
its kind I have seen.”— J. S. Knox, M.D. , Lecturer on Obstetrics, 
Rush Medical College, Chicago. 

Price of each Book, Cloth, $1.00. Interleaved for Notes, $1.25. 




4 


THE ? QUIZ-COMPENDS T. 


“ I have been teaching in this department for many years, and am 
free to say that this will be the best assistant I ever had. It is ac¬ 
curate and comprehensive, but brief and pointed."— Prof. P. D. 
Yost, St. Louis. 

No. 6. MATERIA MEDIOA. Revised Ed. 

A Compend on Materia Medica and Therapeutics, with 
especial reference to the Physiological Actions of 
Drugs. For the use of Medical, Dental, and Pharma¬ 
ceutical Students and Practitioners. Based on the New 
Revision (Sixth) of the U. S. Pharmacopoeia, and in¬ 
cluding many unofficinal remedies. By Samuel O. 
L. Potter, m.a.,m.d., U. S. Army. 

** I have examined the little volume carefully, and find it just 
such a book as I require in my private Quiz, and shall certainly re¬ 
commend it to my classes. Your Compends are all popular here in 
Washington.”— John E. Brackett, M.D., Professor of Materia 
Medica and Therapeutics, Howard Medical College, Washington. 

“ Part of a series of small but valuable text-books. . . . While 
the work is, owing to its therapeutic contents, more useful to the 
medical student, the pharmaceutical student may derive much use¬ 
ful information from it."— N. Y. Pharmaceutical Record. 

No. 7. CHEMISTRY. Revised Ed. 

A Compend of Chemistry. By G. Mason Ward, m.d., 
Demonstrator of Chemistry in Jefferson Medical Col¬ 
lege, Philadelphia. Including Table of Elements and 
various Analytical Tables. 

“ Brief, but excellent. ... It will doubtless prove an admirable 
aid to the student, by fixing these facts in his memory. It is worthy 
the study of both medical and pharmaceutical students in this 
branch.”— Pharmaceutical Record, New York. 

No. 8. VISCERAL ANATOMY. 

SECOND EDITION. ILLUSTRATED. 

A Compend of Visceral Anatomy. By Samuel O. L. 
Potter, m.a., m.d., U. S. Army. With 40 Illustrations. 

*** This is the only Compend that contains full descriptions of the 
viscera, and will, together with No. 1 of this series, form the only 
complete Compend of Anatomy published. 

“ This work is very happily arranged, very thorough in practical 
details, and will no doubt prove universally popular with medical 
students."— Medical Herald. 

“ I believe it will prove of great usefulness to the busy teacher or 
student; short, concise helps are always welcome."— Dr. R. N. 
Hall, Demonstrator of Anatomy, College of Physicians and Sur¬ 
geons, Chicago. 

“ It is a very concise and convenient help to the memory, and 
quite accurate."— Prof. L. B. How , Medical Department, Dart¬ 
mouth College. 

Price of Each Book, Cloth, $1.00. Interleaved for Notes, $1.25. 



THE ? QUIZ-COMPENDS ?. 


5 


No. 9. SURGERY. Second Edition. 

ILLUSTRATED. 

A Compend of Surgery; including Fractures, Wounds, 
Dislocations, Sprains, Amputations and other opera¬ 
tions, Inflammation, Suppuration, Ulcers, Syphilis, 
Tumors, Shock, etc. Diseases of the Spine, Ear, Eye, 
Bladder, Testicles, Anus, and other Surgical Diseases. 
By Orville Horwitz, a.m., m.d., with 62 Illustra¬ 
tions. Second Edition. Enlarged and Revised. 

*** This compend has been prepared with great care, from the 
standard authorities on Surgery and from notes taken by the author 
during attendance on lectures by prominent professors. The rapid 
sale of the first edition allowed the addition of much valuable 
matter, besides a thorough revision of the whole book. 

No. IO. ORGANIC CHEMISTRY. 

A Compend of Organic Chemistry, including Medical 
Chemistry, Urine Analysis, and the Analysis of Water 
and Food, etc. By Henry Leffmann, m.d., Pro¬ 
fessor of Clinical Chemistry and Hygiene in the Phila¬ 
delphia Polyclinic; Professor of Chemistry, Penn¬ 
sylvania College of Dental Surgery; Member of the 
N. Y. Medico-Legal Society. Cloth. $1.00. 

Interleaved, for the addition of Notes, $1.25. 

“ Compact, substantial and exact; well suited as a remembrancer 
to students.”— Pacific Medical and Surgical Journal. 

“ This neat, handy and exceedingly useful volume is a valuable 
aid to the student.”— Pharmaceutical Record. 

“ It contains, in compact form, the most of modern organic and 
medical chemistry essential to the student of medicine, and will be 
of great value in bringing this subject within his grasp.”— C. C. 
Howard, Prof, of Chemistry, Starling Medical College, Colum¬ 
bus, Ohio. 

“It has the decided merit of being written in a clear and under¬ 
standable language.”— Dr. J. Sickels, Instructor in Chemistry, 
University Medical College, New York. 

No. 11. PHARMACY. 

A Compend of Pharmacy. By F. E. Stewart, m.d., 
Ph. G., Quiz Master in Chemistry and Theoretical 
Pharmacy, Philadelphia College of Pharmacy; De¬ 
monstrator and Lecturer in Pharmacology, Medico- 
Chirurgical College; Member of the American Phar¬ 
maceutical Association. 

4 ®“The PQuiz Compends ? are adapted to students of any 
college, because they are based upon the text-books in use through¬ 
out the country. They contain the latest and best information, in 
such a shape that it can be easily memorized. 

Price of Each Book, Cloth, $1.00; Interleaved for Notes $1.25. 



6 


STUDENTS’ TEXT-BOOKS AND MANUALS. 


ANATOMY. 

Holden’s Anatomy. A manual of Dissection of the Human 
Body. Fifth Edition. Enlarged, with Marginal References and 
over 200 Illustrations. Octavo. Cloth, 5.00; Leather, 6.00 

Bound in Oilcloth, for the Dissecting Room, $4.50. 

“ No student of Anatomy can take up this hook without being 
pleased and instructed. Its Diagrams are original, striking and 
suggestive, giving more at a glance than pages of text description. 
* * * The text matches the illustrations in directness of prac¬ 
tical application and clearness of detail .”—New York Medical 
Record. 

Holden’s Human Osteology. Comprising a Description of the 
Bones, with Colored Delineations of the Attachments of the 
Muscles. The General and Microscopical Structure of Bone and 
its Development. With Lithographic Plates and Numerous Illus¬ 
trations. Sixth Edition. 8vo. Cloth, 6.00 

Heath’s Practical Anatomy. Sixth London Edition. 24 Col¬ 
ored Plates, and nearly 300 other Illustrations. Cloth, 5.00 

CHEMISTRY. 

Bartley’s Medical Chemistry. A text-book prepared specially 
for Medical, Pharmaceutical and Dental Students. With 40 
Illustrations, Plate of Absorption Spectra and Glossary of Chemi- 
* cal Terms. Cloth, 2.50 

*** This book has been written especially for students and phy¬ 
sicians. It is practical and concise, dealing only with those parts 
of chemistry pertaining to medicine ; no time being wasted in long 
descriptions of substances and theories of interest only to the 
advanced chemical student. 

Bloxam’s Chemistry, Inorganic and Organic, with Experiments. 

Fifth Edition, nearly 300 Illustrations. Cloth, 3.75 ; Leather, 4.75 
Bowman’s Practical Chemistry. Including Analysis. About 
100 Illustrations. Eighth Edition. Cloth, 2.00 

Muter’s Practical and Analytical Chemistry. 8vo Cloth, 2.50 

Richter’s Inorganic Chemistry. A text-book for Students. 
Second American, from Fourth German Edition. Translated by 
Prof. Edgar F. Smith, ph.d. 89 Wood Engravings and Colored 
Plate of Spectra. Just Ready. Cloth, 2.00 

Richter’s Organic Chemistry, or Chemistry of the Carbon 
Compounds. Translated by Prof. Edgar F. Smith, ph.d. 
Illustrated. Just Ready. Cloth, 3.00 

Trimble. Practical and Analytical Chemistry. A Complete 
Course in Chemical Analysis, by Henry Trimble, Professor of 
Analytical Chemistry in the Philadelphia College of Pharmacy. 
Illustrated. 8vo. Cloth, 1.50 

4®“ See pages 2 to j for list of ? Quiz- Comfends ? 




STUDENTS’ TEXT-BOOKS AND MANUALS. 


7 


Chemistry : — Continued. 

Wolff’s Applied Medical Chemistry. By Lawrence Wolff, 
m.d., Demonstrator of Chemistry in Jefferson Medical College, 
Philadelphia, yust Ready. Cloth, 1.50 

CHILDREN. 

Goodhart and Starr. The Diseases of Children. A Manual 
for Students and Physicians. By J. F. Goodhart, m.d., Physi¬ 
cian to the Evelina Hospital for Children; Assistant Physician 
to Guy’s Hospital, London. American Edition, Revised and 
Edited by Louis Starr, m.d., Clinical Professor of Diseases of 
Children in the Hospital of the University of Pennsylvania; 
Physician to the Children’s Hospital, Philadelphia. Containing 
many new Prescriptions, a List of over 50 Formulae, conforming 
to the U. S. Pharmacopoeia, and Directions for making Artificial 
Human Milk, for the Artificial Digestion of Milk, etc. Just 
Ready. Demi-Octavo, 738 Pages. Cloth, 3.00; Leather, 4.00 
The New York Medical Record says :—“ As it is said of some 
men, so it might be said of some books, that they are ‘ born to 
greatness.’ This new volume has, we believe, a mission, particu¬ 
larly in the hands of the younger members of the profession. In 
these days of prolixity in medical literature, it is refreshing to meet 
with an author who knows both what to say, and when he has said 
it. The work of Dr. Goodhart (admirably conformed, by Dr. Starr, 
to meet American requirements) is the nearest approach to clinical 
teaching, without the actual presence of clinical material, that we 
have yet seen. The details of management so gratefully read by 
the young practitioner are fully elucidated. Altogether, the book 
is one of as great practical working value as we have seen for many 
months.” 

Day. On Children. A Practical and Systematic Treatise. 

Second Edition. 8vo. 752 pages. Cloth, 3.00; Leather, 4.00 
Meigs and Pepper. The Diseases of Children. Seventh 
Edition. 8vo. Cloth, 6.00; Leather, 7.00 

DENTISTRY. 

Flagg’s Plastics and Plastic Filling. 2d Ed. Cloth, 4.00 
Gorgas. Dental Medicine. A Manual of Materia Medica and 
Therapeutics, by Professor F. J. S. Gorgas, m.d., d.d.s , Pro¬ 
fessor of the Principles and Practice of Dental Science, in Den¬ 
tal Department, University of Maryland. 8vo. Second Edition. 
Revised and Enlarged. Cloth, 3.25 

Harris’ Principles and Practice of Dentistry. Including 
Anatomy, Physiology, Pathology, Therapeutics, Dental Surgery 
and Mechanism. Eleventh Edition. Revised and enlarged by 
Professor Gorgas. 744 Illustrations. Cloth, 6.50 ; Leather, 7.50 
Richardson’s Mechanical Dentistry. Third Edition. 185 
Illustrations. 8vo. Cloth, 4.00; Leather, 4.75 

Stocken’s Dental Materia Medica. Third Edition. Cloth, 2.50 
See pages 2 to 5 for list 0/ ? Quiz- Cofupends ? 



8 


STUDENTS’ TEXT-BOOKS AND MANUALS. 


Dentistry :— Continued. 

Tomes’ Dental Anatomy, Human and Comparative. Sec¬ 
ond Edition. 191 Illustrations. Cloth, 4.25 

Tomes’ Dental Surgery. New Revised Edition. Preparing. 

Taft’s Operative Dentistry. A Text-book for Dental Students 

and Practitioners. Fourth Edition. Over 100 Illustrations. 

Cloth, 4.25 ; Leather, 5.00 

DICTIONARIES. 

Cleaveland’s Pocket Medical Lexicon. Thirty-first Edition. 
Giving correct Pronunciation and Definition of Terms used in 
Medicine and the Collateral Sciences. Very small pocket size, 
red edges. Cloth, .75 ; pocket-book style, 1.00 

Longley’s Pocket Dictionary. The Student’s Medical Lexicon, 
giving Definition and Pronunciation of all Terms used in Medi¬ 
cine, with an Appendix giving Poisons and Their Antidotes, 
Abbreviations used in Prescriptions, Metric Scale of Doses, etc. 
24mo. Cloth, 1.00; pocket-book style, 1.25 

Harris’ Dictionary of Medical Terminology and Dental Surgery 
By Prof. Gorgas. Fourth Edition. Cloth, 6.50; Leather, 7.50 

EYE. 

Arlt. Diseases of the Eye. Including those of the Conjunc¬ 
tiva, Cornea, Sclerotic, Iris and Ciliary Body. By Professor 
Fred. Ritter von Arlt. Translated by Dr. Lyman Ware. Illus¬ 
trated. 8vo. Cloth, 2.50 

Higgins. Ophthalmic Practice. A Handbook for Students 
and Practitioners. i6mo. Cloth, .50 

Macnamara. On Diseases of the Eye. Fourth Edition, 
revised, with Marginal References, numerous Colored Plates and 
Diagrams, Wood Cuts and Test Types. Cloth, 4.00 

HYGIENE. 

Parke’s Practical Hygiene. Sixth Edition, enlarged. Illus¬ 
trated. 8vo. Cloth, 3.00 

Wilson’s Handbook of Hygiene and Sanitary Science. 
Fifth Edition. Revised and Illustrated. Cloth, 2.75 

MATERIA MEDICA AND THERAPEUTICS. 

Biddle’s Materia Medica. Tenth Edition. For the use of 
Students and Physicians. By the late Prof. John B. Biddle, m. d.. 
Professor of Materia Medica in Jefferson Medical College, Phila¬ 
delphia. The Tenth Edition, thoroughly revised, and in many 
parts rewritten, by his son, Clement Biddle, m.d., Past Assistant 
Surgeon, U. S. Navy, assisted by Henry Morris, m.d., Demon¬ 
strator of Obstetrics in Jefferson Medical College. 8vo., illus¬ 
trated. Just Ready. Cloth, 4.00 ; Leather, 4.75 

See pages 2 to 5 for list of ? Quiz-Comp ends ? 



STUDENTS’ TEXT-BOOKS AND MANUALS. 


9 


Biddle’s Materia, Medica and Therapeutics : — Continued. 

“ The larger, works usually recommended as text-books in our 
medical schools are too voluminous for convenient use. This work 
will be found to contain in a condensed form all that is most valuable, 
and will supply students with a reliable guide.”— Chicago Med. Jl. 

Merrell’s Digest of Materia Medica. 8vo. Half Calf, 4.00 

Roberts’ Compend of Materia Medica and Pharmacy. By the 
author of “ Roberts' Practice.” Cloth, 2.00 

“ It contains an immense amount of matter.” —The National 
Druggist. 

Headland’s Action of Medicines. 9th Ed. 8vo. Cloth, 3.00 
Waring. Therapeutics. A Practical Manual. Fourth Edition, 
revised and enlarged. In Press. 

MEDICAL JURISPRUDENCE. 

Reese. A Text-book of Medical Jurisprudence and Toxi¬ 
cology. By John J. Reese, m.d.. Professor of Medical Juris¬ 
prudence and Toxicology in the Medical and Law Departments 
of the University of Pennsylvania ; Vice-President of the Med¬ 
ical Jurisprudence Society of Philadelphia; Physician to St. 
Joseph’s Hospital; Corresponding Member of The New York 
Medico-legal Society. Demi-Octavo. Cloth, 4.00; Leather, 5.00 
“ Professor Reese is so well known as a skilled medical jurist, 
that his authorship of any work virtually guarantees the thorough¬ 
ness and practical character of the latter. And such is the case in 
the book before us. * * * * We might call these the essentials 
for the study of medical jurisprudence. The subject is skeletonized, 
condensed, and made thoroughly up to the wants of the general 
medical practitioner, and the requirements of prosecuting and de¬ 
fending attorneys. If any section deserves more distinction than 
any other, as to intrinsic excellence, it is that on toxicology. This 
part of the book comprises the best outline of the subject in a 
given space that can be found anywhere. As a whole, the work is 
everything it promises, and more, and considering its size, con¬ 
densation, and practical character, it is by far the most useful one 
for ready reference, that we have met with. It is well printed and 
neatly bound.”— New York Medical Record. 

Abercrombie’s Students’ Guide to Medical Jurisprudence. 

i2mo. Cloth, 2.50 

Mann’s Manual of Psychological Medicine, and Allied Ner¬ 
vous Diseases. Their Diagnosis, Pathology and Treatment, and 
their Medico-Legal Aspects. Illustrated. 8vo. 

Cloth, 5.00; Leather, 6.00 

Woodman and Tidy’s Medical Jurisprudence and Toxi¬ 
cology. Chromo-Lithographic Plates and 116 Wood engravings. 

Cloth, 7.50; Leather, 8.50 
See pages 2 to 5 for list of ?Quiz-Compends? 



10 STUDENTS’ TEXT-BOOKS AND MANUALS. 


MISCELLANEOUS. 

Beale. Slight Ailments. Their Nature and Treatment. Illus¬ 
trated. 8vo. Paper cover, .75 ; Cloth, 1.25 

Dulles. Surgical and other Emergencies. Illustrated. Sec¬ 
ond Edition. i2tno. Cloth,.75 

Fothergill. Diseases of the Heart and Their Treatment. 

Second Edition. 8vo. Cloth, 3.50 

Tanner. Memoranda of Poisons. Their Antidotes and Tests. 

Fifth Edition, nmo. Cloth, .75 

Allingham. Diseases of the Rectum. Fourth Edition. Illus¬ 
trated. 8vo. Paper covers, .75; Cloth, 1.25 

OBSTETRICS AND GYNAECOLOGY. 

Byford. The Diseases of Women. By W. H. Byford, a.m., 
m.d., Professor of Gynaecology in Rush Medical College ; of 
Obstetrics in the Woman’s Medical College ; and Surgeon to the 
Woman’s Hospital, Chicago. Third Edition. Over 160 Illus¬ 
trations. Octavo. Cloth, 5.00 ; Leather, 6.00 

“ The treatise is as complete a one as the present state of our 
science will admit of being written. We commend it to the diligent 
study of every practitioner and student, as a work calculated to in¬ 
culcate sound principles and lead to enlightened practice.”— New 
York Medical Record. 

Cazeaux and Tarnier. Obstetrics; the Theory and Practice 
of; including the Diseases of Pregnancy and Parturition, Ob¬ 
stetrical Operations, etc. By P. Cazeaux, Member of the Impe¬ 
rial Academy of Medicine, etc. Revised, with additions, by 
S. Tarnier, Prof, of Obstetrics and Diseases of Women and 
Children in the Faculty of Medicine, of Paris. A New Ameri¬ 
can, from the Eighth French and First Italian Editions. Edited 
and enlarged by Robert J. Hess, m.d.. Physician to the North¬ 
ern Dispensary, Philadelphia; Member of the College of Physi¬ 
cians of Philadelphia, etc. 1100 pages, 4to, with 12 Full-page 
Lithographic plates, 5 of which are Colored, and over 175 Wood 
Engravings. 

Sold by subscription only. Full information and Four-page 
Circular upon application to the publishers. 

“ I have examined this edition of Cazeaux and Tarnier’s Theory 
and Practice of Obstetrics, just from the publishing house of 
P. Blakiston, Son & Co., Philadelphia, and pronounce it practical 
and just what is needed by every practitioner. I highly recommend 
the work. It should be prominent in every library.”— T. Gaillard 
Thomas, M. D.. Professor of GyncECology in College of Physicians 
and Surgeons , New York. 

Gallabin’s Midwifery. A New Manual for Students. Illus¬ 
trated. In Press. 

WiP See pages 2 to 5 for list of ? Quiz- Lompends ? 



STUDENTS’ TEXT-BOOKS AND MANUALS. 


II 


Obstetrics and Gyncecology: — Continued. 

Meadows’ Manual of Midwifery. Including the Signs and 
Symptoms of Pregnancy, Obstetric Operations, Diseases of the 
Puerperal State, etc. 145 Illustrations. 494 pages. Cloth, 2.00 
Rigby’s Obstetric Memoranda. 4th Ed. 32mo. Cloth, .50 
Swayne’s Obstetric Aphorisms. For the use of Students 
commencing Midwifery Practice. 8th Ed. i2mo. Cloth, 1.25 

PATHOLOGY AND HISTOLOGY. 

Rindfleisch’s General Pathology. For Students and Physi¬ 
cians. By Prof. Edward Rindfleisch, of Wurzburg. Trans¬ 
lated by Wm. H. Mercur, M.p., of Pittsburg, Pa., Edited by 
James Tyson, m.d., Professor of Pathology and Morbid Anatomy 
in the University of Pennsylvania. i2mo. Cloth, 2.00 

Gilliam’s Essentials of Pathology. A Handbook for Students. 
47 Illustrations. i2mo. Cloth, 2.00 

*** The object of this book is to unfold to the beginner the funda¬ 
mentals of pathology in a plain, practical way, and by bringing 
them within easy comprehension to increase his interest in the study 
of the subject. Though it will not altogether supplant larger works, 
it will be found to impart clear-cut conceptions of the generally 
accepted doctrines of the day, and to prevent confusion in the mind 
of the student. 

Gibbes’ Practical Histology and Pathology. Third Edition. 
Enlarged. i2mo. Cloth, 1.75 

PHYSICAL DIAGNOSIS. 

Bruen’s Physical Diagnosis of the Heart and Lungs. By 

Dr. Edward T. Bruen, Assistant Professor of Clinical Medicine 
in the University of Pennsylvania. Second Edition, revised. 
With new Illustrations. i2mo. Cloth, 1.50 

***The subject is treated in a plain, practical manner, avoiding 
questions of historical or theoretical interest, and without laying 
special claim to originality of matter, the author has made a book 
that presents to the student the somewhat difficult points of Physi¬ 
cal Diagnosis clearly and distinctly. 

PHYSIOLOGY. 

Yeo’s Physiology. The most Popular Students’ Book. By 
Gerald F. Yeo, m.d., f.r.c.s.. Professor of Physiology in King’s 
College, London. Small Octavo. 750 pages. Over 300 carefully 
printed Illustrations. With a Full Glossary and Index. 

Cloth, 4.00; Leather, 5.00 
“ The work will take a high rank among the smaller text-books 
of Physiology.”— Pro/. H. P. Bowditck, Harvard Med. School, 
Boston. 

“ The brief examination I have given it was so favorable that I 
placed it in the list of text-books recommended in the circular ot 
the University Medical College.”— Prof. Lewis A. Stimpson , 
M. D., 37 East 33d Street, New York. 

See pages 2 to 3 /or list 0/ ? Quiz- Covipends ? 



12 STUDENTS’ TEXT-BOOKS AND MANUALS. 


Physiology :— Continued. 

Kirke’s Physiology, nth Ed. Illus. Cloth, 4.00; Leather, 5.00 
Landois’ Human Physiology. Including Histology and Micro¬ 
scopical Anatomy. 2 volumes. Cloth, 10.00 

“ So great are the advantages offered by Prof. Landois’ Text¬ 
book, from the exhaustive and eminently practical manner in which 
the subject is treated, that, notwithstanding it is, one of the largest 
works on Physiology, it has yet passed through four large editions 
in the same number of years. Dr. Stirling’s annotations have 
materially added to the value of the work. . . . Admirably 

adapted for the practitioner. . . . With this Text-book at his 

command, no student could fail in his examination.”— Lancet. 

Sanderson’s Physiological Laboratory. Being Practical Ex¬ 
ercises for the Student. 350 Illustrations. 8vo. Cloth, 5.00 
Tyson’s Cell Doctrine. Its History and Present State. Illus¬ 
trated. Second Edition. Cloth, 2.00 

PRACTICE. 

Roberts’ Practice. Fifth American Edition. A Handbook 
of the Theory and Practice of Medicine. By Frederick T. 
Roberts, m.d. ; m.r.c.p., Professor of Clinical Medicine and 
Therapeutics in University College Hospital, London. Fifth 
Edition. Octavo. Cloth, 5.00; Leather, 6.00 

*** This new edition has been subjected to a careful revision. 
Many chapters have been rewritten. Important additions have 
been made throughout, and new illustrations introduced. Recom¬ 
mended as a Text-book at University of Pennsylvania, Long Island 
College Hospital, Yale and Harvard Colleges, Bishop’s College, 
Montreal, University of Michigan, and over twenty other Medical 
Schools. 

“ I have become thoroughly convinced of its great value, and 
have cordially recommended it to my class in Yale College .”— 
Prof. David P. Smith. 

“ I have examined it with some care, and think it a good book, 
and shall take pleasure in mentioning it among the works which 
may properly be put in the hands of students.”— A. B. Palmer, 
Prof, of the Practice of Medicine, University of Michigan. 

“ A clear, yet concise, scientific and practical work. It is a capi¬ 
tal compendiun of the classified knowledge of thesubject.”— Prof. 
J. Adams Allen, Rush Medical College, Chicago. 

“ It is unsurpassed by any work that has fallen into our hands, 
as a compendium for students preparing for examination. It is 
thoroughly practical, and fully up to the times.”— The Clinic. 
Aitken’s Practice of Medicine. Seventh Edition. 196 Illus¬ 
trations. 2 vols. Cloth, 12.00; Leather, 14.00 

Fagge’s Principles and Practice of Medicine. A Complete 
Text-book. 2 vols. Now Ready. 

Tanner’s Index of Diseases, and Their Treatment. Cloth, 3.00 
“ This work has won for itself a reputation. ... It is, in 
truth, what its Title indicates.”— N. Y. Medical Record. 

tidy' See pages 2 to 5 for list of ?Quiz-Compends ? 



STUDENTS’ TEXT-BOOKS AND MANUALS. 13 


PRESCRIPTION BOOKS. 

Wythe’s Dose and Symptom Book. Containing the Doses 
and Uses of all the principal Articles of the Materia Medica, etc. 
Sixteenth edition. 32mo. Cloth,i.oo; Pocket-book style, 1.25 
Pereira’s Physician’s Prescription Book. Containing Lists 
of Terms, Phrases, Contractions and Abbreviations used in 
Prescriptions, Explanatory Notes, Grammatical Construction of 
Prescriptions, etc., etc. By Professor Jonathan Pereira, m.d. 
Sixteenth Edition. 321110. Cloth, 1.00; Pocket-book style, 1.25 

SKIN DISEASES. 

Van Harlingen on Skin Diseases. A Handbook of the Dis¬ 
eases of the Skin, their Diagnosis and Treatment. By Arthur 
Van Harlingen, m.d., Prof, of Diseases of the Skin in the Phila¬ 
delphia Polyclinic; Consulting Physician to the Dispensary 
for Skin Diseases, etc. With colored plates. i2mo. Cloth, 1.75 
***This is a complete epitome of skin diseases, arranged in 
alphabetical order, giving the diagnosis and treatment in a concise, 
practical way. Many prescriptions are given that have never been 
published in any text-book, and an article incorporated on Diet. 
The plates do not represent one or two cases, but are composed of 
a number of figures, accurately colored, showing the appearance of 
various lesions, and will be found to give great aid in diagnosing. 

“ This new handbook is essentially a small encyclopaedia. * * * 
We heartily commend it for its brevity, clearness and evidently 
careful preparation.”— Philadelphia Medical Times. 

“ This is an excellent little book, in which, for ease of reference, 
the more common diseases of the skin are arranged in alphabetical 
order, while many good prescriptions are given, together with clear 
and sensible directions as to their proper application.”— Boston 
Medical and Surgical Journal. 

Bulkley. The Skin in Health and Disease. By L. Duncan 
Bulkley, Physician to the N. Y. Hospital. Illus. Cloth, .50 

SURGERY. 

Heath’s Minor Surgery, and Bandaging. New Edition. With 
many Illustrations. In Press. 

Mears’ Practical Surgery. Second Edition. Enlarged. 490 
Illustrations. Cloth, $3.75; Leather, $4.75 

Pye’s Surgical Handicraft. A Manual of Surgical Manipula¬ 
tions, Minor Surgery, Bandaging, Dressing, etc., etc. With 
special chapters on Aural Surgery, Extraction of Teeth, Anaes¬ 
thetics, etc. 208 Illustrations. 8vo. Cloth, 5.00 

Watson on Amputation of the Extremities, and their Compli¬ 
cations. 2 colored plates and 250 wood cuts. 8vo. Cloth, 5.50 
4 F 3 r* See I ages 2 to 5 for list 0/ ? Quiz-Compends f 



14 STUDENTS’ TEXT-BOOKS AND MANUALS. 


THROAT. 

Mackenzie on the Throat and Nose. By Morell Mackenzie, 
m.d.. Senior Physician to the Hospital for Diseases of the Chest 
and Throat; Lecturer on Diseases of the Throat at the London 
Hospital, etc. 

Vol. I. Including the Pharynx, Larynx, Trachea, etc., with 
Formulae and 112 Illustrations. 

Vol. II. Diseases of the CEsophagus, Nose and Naso-Pharynx, 
with Formulae and 93 Illustrations. 

The two volumes, Cloth, 6.00; Leather, 7.50 
Vol. II, separately, Cloth, 3 00; Leather, 4.00 

“ It is both practical and learned; abundantly and well illustrated; 
its descriptions of disease are graphic and the diagnosis the best we 
have anywhere seen.”— Philadelphia Medical Times. 

Cohen. The Throat and Voice. Illustrated. Cloth, .50 

James. Sore Throat. Its Nature, Varieties and Treatment. 
121T10. Illustrated. Paper cover, .75; Cloth, 1.25 

URINE AND URINARY ORGANS. 

Acton. The Reproductive Organs. In Childhood, Youth 
Adult Life and Old Age. Sixth Edition. Cloth, 2.00 

Beale. Urinary and Renal Diseases and Calculous Disorders. 
Hints on Diagnosis and Treatment. i2mo. fust Ready. 

Cloth, 1.75 

Ralfe. Kidney Diseases and Urinary Derangements. 42 Illus¬ 
trations. i2mo. 572 pages, yust Ready. Cloth, 2.75 

Legg. On the Urine. A Practical Guide. Sixth Edition. 

i2mo. Cloth, .75 

Marshall and Smith. On the Urine. The Chemical Analysis 
of the Urine. By John Marshall, m.d., Chemical Laboratory, 
University of Pennsylvania, and Prof. E. F. Smith, ph.d. With 
Colored Plates. Cloth, 1.00 

Thompson. Diseases of the Urinary Organs. Seventh 
Edition. Illustrated. Cloth, 1.25 

Tyson. On the Urine. A Practical Guide to the Examination 
of Urine. For Physicians and Students. By James Tyson, m.d., 
Professor of Pathology and Morbid Anatomy, University of 
Pennsylvania. With Colored Plates and Wood Engravings. 
Fifth Edition. Revised and Enlarged. i2mo. Cloth, 1.50 

Durkee. On Gonorrhoea and Syphilis. Illus. Cloth, 3.50 

>6®=* See pages 2 to 5 for list of ? Quiz- Compends ? 



Richter’s Chemistries. 

AUTHORIZED TRANSLATIONS. 


By EDGAR F. SMITH, M.A., Ph.D., 

Prof, of Chemistry in Wittenberg College, Springfield, Ohio; 
formerly in the Laboratories of the University of Pennsylva¬ 
nia and Muhlenburg College; Member of the Chemical 
Societies of Berlin and Paris ; of the Academy of 
Natural Sciences of Philadelphia, etc., etc. 

EACH VOLUME SOLD SEPARATELY. 

INORGANIC CHEMISTRY. Second American, 
from the Fourth German Edition; thoroughly revised 
and in many parts rewritten. With 89 Illustrations 
and Colored Plate of Spectra. Cloth, $2.00 

THE CHEMISTRY OF THE CARBON COM¬ 
POUNDS, or Organic Chemistry. First Ameri¬ 
can, from Fourth German Edition. Illustrated. 

Cloth, $3.00 

The success attending the publication of the first edi¬ 
tion of Richter’s Inorganic Chemistry encourages the 
translator and publishers to believe that the companion 
volume will have an equally warm reception. Professor 
Richter’s methods of arrangement and teaching have 
proved their superiority, abroad, by the very large sale 
of his books all over the Continent, translations having 
been made in Germany, Russia, Holland and Italy. 

From Prof. B. Silliman, Yale College, New Haven, Conn. 

“It is decidedly a good book, and in some respects the best 
manual we have.” 

From John Marshall, m.d., nat. sc. d. (Tubingen), Demonstra¬ 
tor of Chemistry in the University of Pennsylvania, Medical 
Department. 

“ The work is of undoubted value. The theory of chemistry, 
which is generally the bugbear of students, is, in this book, very 
clearly explained, and the explanations are so well distributed 
through the book that students are brought easily from the simplest 
to the most difficult problems. 

“ That part descriptive of the elements and their compounds is 
full, and all that could be desired in a text-book, while the cuts, 
with which the work is profusely illustrated, are an excellent aid to 
the student. Altogether, it is one of our best modern works on 
chemistry." 



Yeo’s Physiology. 

A MANUAL FOR STUDENTS. 


By GERALD F. YEO, M.D., F.R.C.S., 

Professor of Physiology in King’s College, London. 

WITH OVER 300 CAREFULLY PRINTED ILLUSTRA¬ 
TIONS AND A GLOSSARY. 

Small Octavo. Cloth, $ 4 . 00 ; Leather, $ 5 . 00 . 

RECOMMENDATIONS. 

“After a careful examination of this manual of Physiology, I can 
truthfully say that it is a most valuable addition to the list of text¬ 
books upon this subject. That it should and will receive a welcome 
from both students and teachers there can be no doubt; for, in addi¬ 
tion to the familiar but well presented facts of most text-books, it 
contains all the more important facts of physiological science which 
have been established in the last few years. The author presents 
his subject in a manner that is clear, concise and logical. Each 
section has had a careful revision, and reveals the author’s famili¬ 
arity with the scope and tendencies of modern physiology. It will 
prove an interesting and instructive book to those commencing the 
study of this subject.’’— A. P. Brubaker, m.d., Demonstrator of 
Physiology at Jefferson Medical College, Philadelphia. 

The writer has endeavored to‘avoid theories which have not 
borne the test of time, and such details of methods as are unnecessary 
for junior students.' His experience as a teacher and as an ex¬ 
aminer has led him to lay stress on the points which are hard to 
grasp and are commonly misunderstood, and he has directed atten¬ 
tion more to those subjects which have a practical medical or surgi¬ 
cal application than to those relating to abstract physiological 
subjects. * * * We have pleasure in recommending this book, as a 
most excellent manual, being what it pretends to be—elementary, 
and yet containing all that is really cf importance to the student of 
medicine. It is difficult to devise an original method of treating 
such a well worn subject as physiology, but the present volume 
undoubtedly has originality in its method. We think the author 
treats his subject in the best manner possible when he combines 
microscopical anatomy intimately with the discussion of strict phy¬ 
siology.”— The Medical Times and Gazette. 




VAN HARLINGEN 


On Skin Diseases. 

WITH COLORED ILLUSTRATIONS. 

A HANDBOOK OF THE DISEASES OF THE SKIN, their Diagnosis 
and Treatment. By Arthur Van Harlingen, m.d., Professor of Dis¬ 
eases of the Skin in the Philadelphia Polyclinic, Consulting Physician to 
the Dispensary for Skin Diseases, etc. Illustrated by colored lithographic 
plates. 

12mo. 284 pages. Cloth. Price, $1.76. 


“ It' is a most useful compen the present time upon the 

important subjects to which it is devoted; and is in all respects a credit to the well recog¬ 
nized abilities of its author.”— James Nevins Hyde, M.D., Professor of Skin and Vent- 
real Diseases, Rush Medical College, Chicago. 

“ This new handbook is essentially a small encyclopedia of pathology and treatment of 
Skin Diseases, in which the subjects are arranged alphabetically. This arrangement was that 
followed by the late Tilbury Fox, of London, in his handbook, which we believe was re¬ 
markably successful; and we have no doubt it will be equally appreciated in the present 
work, which (compendious in form) contains a very complete summary of the present state 
of dermatology. Dr. Van Harlingen’s position in the profession, being at present vice- 
president of the American Dermatological Association, which he served as secretary for 
several years, and the high standard of his communications to his department, are sufficient 
to warrant the confidence in his teachings, which is fully sustained by an examination of this 
handbook, which we heartily commend for its brevity, clearness and evident careful prepa¬ 
ration.”— Philadelphia Medical Times, October 18th, 1884. 


RINDFL.EISCH. 

The Elements of Pathology. 

A Text-Book in the University of Pennsylvania. 

THE ELEMENTS OF PATHOLOGY. For Students and Physicians. 
By Edward Rindfleisch, m.d., Professor of Pathological Anatomy in 
the University of Wurzburg. Anthorized translation by William H. 
Mercur, m.d., of Pittsburgh, Pa. Revised by James'Tyson, m.d., Pro¬ 
fessor of General Pathology and Morbid Anatomy in the University of 
Pennsylvania. 

12mo. 263 pages. Cloth, $2.00. 


0 

‘•The practical views of ?r^^f^W)^l^l^l^fi?Ai?ofeQ^Sstologists is placed before the 
profession in this admirable work, in a most careful and systematic manner. The author, who 
is one of the leading pathologists, sets forth not only the ground-work in his department, 
but treats and makes clear many of the more difficult points of the study of pathological 
processes. The work is divided into a consideration,yfr^, of the local outbreak of diseases ; 
second, into the anatomical extension of disease; thirdly, into the physiological extension 
of disease, and lastly, into an examination of special parts.”— The Medical Bulletin. 


P. BLAKISTON, SON Sl CO., Publishers and Booksellers, 

1012 WALNUT STREET. PHILADELPHIA. 






BIDDLE’S 

Materia Medica. 

TENTH REVISED EDITION. 

Contains all Changes in the New Pharmacopoeia. 

Recommended as a Text-book at Yale College, University of Michigan, 
College of Physicians and Surgeons, Baltimore, Baltimore Medical 
College, Louisville Medical College, and a number of other 
Colleges throughout the United States. 

BIDDLE’S MATERIA MEDICA, For the Use of Students 
and Physicians. By the late Prof. John B. Biddle, m.d., 
Professor of Materia Medica in Jefferson Medical College, 
Philadelphia. The Tenth Edition, thoroughly revised, and 
in many parts rewritten, by his son, Clement Biddle, m.d., 
Assistant Surgeon, U. S. Navy, assisted by Henry Morris, 
m.d. , Demonstrator of Obstetrics, Jefferson Medical College, 
Philadelphia. Containing all the additions and changes made 
in the last revision of the United States Pharmacopoeia. 8vo. 

Bound in Cloth. Price $4.00; Leather, $4.75. 

RECOMMENDATIONS. 

“ It will be found a useful handbook by students, especially, who may be 
under the instruction of its able and accomplished author.”— American Med¬ 
ical Journal. 

“ In short, it is just the work for a student, embracing as it does what will 
be discussed in a course of lectures on materia medica.”— Cincinnati Medical 
News. 

“ In truth, the work is well adapted to the wants of students.”— The Clinic. 

“ Nothing has escaped the writer’s scan. All the new remedies against 
disease are duly and judiciously noted. Students will certainly appreciate its 
shapely form, grace of manner, and general multum inparvo style.”— Ameri¬ 
can Practitioner. 

“ Biddle’s ‘ Materia Medica ’ is well known to the profession, being a stand¬ 
ard text-book in several leading colleges.”— New York Medical Journal. 

“ It contains, in a condensed form, all that is valuable in materia medica, 
and furnishes the medical student with a complete manual on this subject.”— 
Canada Lancet. 

“ The necessity for a new edition of this work in so short a time is the best 
proof of the value in which it is held by the profession.”— Medical and Surg¬ 
ical Reporter. s 

“ The standard * Materia Medica ’ with a large number of medical students 
is Biddle’s.”— Buffalo Medical and Surgical Journal. 

“The larger works usually recommended as text-books in our medical 
schools are too voluminous for convenient use. This work will be found to 
contain in a condensed form all that is most valuable, and will supply students 
with a reliable guide.”— Chicago Medical Journal. 

*** This Ninth Edition contains all the additions and changes in the U. S. 
Pharmacopoeia, Sixth Revision. 


P. BLAKISTON, SON A CO., Publishers and Booksellers, 

1012 WALNUT STREET, PHILADELPHIA. 




REESE'S 

Medical Jurisprudence 

. AND 

TOXICOLOGY. 

A TEXT-BOOK FOR STUDENTS AND PHYSICIANS. By John J. 
Reese, m.d., Professor of Medical Jurisprudence and Toxicology in the 
University of Pennsylvania; Vice-President of the Medical Jurisprudence 
Society of Philadelphia; Member of the College of Physicians of Phila¬ 
delphia; Corresponding Member of the New York Medico-Legal Society 
606 pages. Demi-octavo. 

Bound in Cloth, $4.00; Leather, $B.OO. 


RECOMMENDATIONS. 

“ I have just concluded a careful review of Dr. John J. Reese’s * Text-Book of Medical 
Jurisprudence and Toxicology,’ and I take great pleasure in saying that it is by far the 
best book of its size on this subject which I have ever seen. * * * It is, for the medical 
student and the general practitioner, a much more convenient, readable, and in most respects 
better book than the voluminous treatises, to say nothing of the fact that it is a much less 
costly book than are these.”— Willis G. Tucker, M. D ., Professor of Inorganic and Ana¬ 
lytical Chetnistry and Medical Jurisprudence, Albany Medical College. 

“ There has long been needed a work like this one. The student of the subject has had to 
choose between very prolix and expensive treatises by American writers, or those prepared 
by foreigners, whose customs and laws differ so much from ours that it materially detracts 
from their usefulness. 

“ In this single volume, printed in clear type and on excellent paper, Dr. Reese presents 
all that the student or the general practitioner will have occasion to learn about the sub¬ 
ject.”— The Medical and Surgical Reporter, Philadelphia, October nth, 1884. 

“ I have examined the work, and find it to be a well compiled manual of the various doc¬ 
trines obtaining, both in law and in medicine, upon the subject of which it treats. In a field 
so wide as that of medical jurisprudence, it is a matter largely of individual choice as to the 
scope which shall be given by an author to the treatment of its several topics. Professor 
Reese seems to me to have struck the golden mean in this respect, and to have combined 
lucidity of style with brevity of statement, so as to give to each topic its due proportion of 
development. It cannot fail to become a most useful handbook for students who desire to 
have in outline the whole body of medical jurisprudence, including even the special depart¬ 
ment of toxicology, with all which that now embraces.”— John Ordronaux, Professor 
of Medical Jurisprudence in Columbia College, New York, and in Dartmouth College , 
Hanover, N. H. 

“ It may be called a practical encyclopaedia, giving just those things which are wanted 
in medico-legal inquiries. * * * * The thoroughness and skill of the author is ap¬ 
parent on every page, and the work may be especially commended as the best single volume 
on this subject in print.”— Quarterly Journal of Inebriety, October, 1884. 

“ It not only treats of the medical side of the subject, but gives much valuable legal infor¬ 
mation as to the rights and duties of physicians in such cases.”— Popular Science News , 
October, 1884. 

“ It comes to the profession at an opportune time, as a valuable addition to the subject of 
State medicine, and the volume should be in the hands of every medical man Prof James 
P. Harrison, University of Virginia. 

“ We might call these the essentials for the study of medical jurisprudence. * * * * 
If any section deserves more distinction than any other, as to intrinsic excellence, it is that 
on toxicology. This part of the book comprises the best outline of the subject in a given 
space that can be found anywhere. As a whole, the work is everything it promises and 
more, and considering its size, condensation and practical character, it is by far the most 
useful one for ready reference that we have met with. It is well printed and neatly bound.” 
— N. Y. Medical Record, Sept. 13th, 1884. 


P. BLAKISTON, SON & CO., Publishers and Booksellers* 

1012 WALNUT STREET, PHILADELPHIA. 





































